How to Choose a Mobile Phone

When choosing a phone, one of the first steps is to choose the size of the display, and mobile phone screen sizes are constantly increasing over time. Hand in hand with this, mobile phone dimensions are also growing, but not as significantly as it might seem, because manufacturers are releasing phones with thinner bezels. The term frameless phones has been used for such devices. A larger display is placed in the same body, which is practical and at the same time looks great.

Today, the screen aspect ratio of 18:9 (or 19:9, 19.5:9, etc.) is common, replacing the obsolete 16:9. These elegant, long phones are easier to hold in one hand and beautifully display various visual content, while keeping the same width.

A common design element is a display cut-out, commonly known as a notch. In each phone, it has a different shape or location. From a functional point of view, it doesn't matter if it is in the middle or on the side. Usually, they contain hidden selfie cameras or sensors for unlocking the phone with your face. However, manufacturers would prefer to get rid of notches completely so that nothing “disturbs“ the look of the display. Therefore, there have been experiments with cameras located behind the display layer of the screen. Nevertheless, customers still need to wait for their introduction to the regular market.

Smartphone display sizes

• 4.4" and less – These phones are rare nowadays. Their representatives include for example the rugged Cubot King Kong Mini or Alcatel U3 2019.
• 4.5" to 5.4" – these small phones can be easily operated with one hand. These are for example the iPhone 12 mini or the rugged CAT S31. In the past, phones of this size  were considered large but today they are relatively small. They do still have lots of fans though.
• 5.5" to 5.9" – a range of diagonals, which were still considered large in 2015, but today we consider them to be medium-sized. This category includes for example the Google Pixel 4a or the iPhon 11 Pro. You may struggle with one-hand operation here, but it is still possible.
• 6" to 6.4" – one of the most popular diagonals. They offer a size compromise for easy operation while watching movies, playing games, surfing the Internet and more. You may find it interesting that some of these phones boast compact dimensions.
• 6.5" and more – This diagonal is used by most flagship manufacturers, but a lot of mid-range phones have it, too. Its advantage is, of course, a large display area, but also larger batteries and therefore a longer battery life.

A larger diagonal does not always mean a larger device. Many phones have reduced frame sizes to a minimum, so a larger display can fit into a body of almost the same size. The following illustration shows two mobiles of similar height. See how the thin frame enables the phone on the right to boast a much larger display.

You can also check the following tables.

Examples of phones with large frames:

Examples of thin-frame phones:

In the last few years, the ratio of the display size to the total size of the phone's body has grown considerably. However, the total dimensions have largely remained the same. For example, last year's iPhone 11 Pro is slightly smaller than the Sony Xperia Z3 from 2014 even though it has a larger display. Similarly, the iPhone 8 Plus has a 5.5" screen while the newer iPhone 11 Pro Max is just as big (maybe even slightly smaller) but boasts a 6.5" display.

So, when you see a large display diagonal, it does not necessarily mean that you are buying a great big brick of a phone. Check out the dimensions of your smartphone. You may find that a 6-inch phone can be a pretty compact device.

Screen technology

OLED screens are the best on the market. They are divided into two categories based on the matrices used.

• AMOLED - they contain an active matrix. They differ from other imaging technologies due to their incredibly faithful black colour rendering, which results in unrivalled contrast. This includes wide viewing angles, low battery usage and low response.

• P-OLED - passive matrix screens. There are simpler and cheaper designs. They are mainly used in smartwatches and small displays.

• Super AMOLED - is a patent of Samsung. The touch sensors are directly on the AMOLED panel, which allowed Samsung to narrow the AMOLED displays of its phones to a minimum.
  

LCD screens generally have a higher power consumption than OLED screens. However, their design is much cheaper, and therefore we see LCD screens in cheaper models.

• Super LCD - popular for their bright colour display and low power consumption. The minimum distance between the screen itself and the cover glass is a great advantage.

• IPS - A very authentic display of a wide range of colours with the best viewing angles. It is the most widespread technology among mobile phones and can be found on most mid-range models.

• TFT - although not a new technology, especially lower middle class models have been returning to it recently. Although the quality does not reach the level of IPS panels, it boasts faster response times preferred by some users.
  

• TN - An older LCD technology, widely used especially for desktop monitors. They are inexpensive to produce, have high brightness, and are less demanding on battery life. However, the poor viewing angles can be a disadvantage. We can find them mainly in older and cheaper phones and tablets.

Display aspect ratio

There are several aspect ratios. There are no limitations, and manufacturers often experiment. In most cases, however, you will encounter:

• 18:9 - A modern aspect ratio that appears on the vast majority of today's smartphones.
• 18.5:9 - mobile brands have tried to make themselves stand out from the crowd with many subtle variations on the classic 18:9 ratio. However, in no way does it mean that you should avoid this ratio.
• 19:9 - Common ratio, which sometimes grows to 19.5:9. The larger the ratio, the more elongated the display.
• 16:9 - an obsolete ratio you won't even find on new phones these days.
• 4:3 - an older ratio, which can be seen on push-button phones.

Most common resolutions

The higher the resolution, the sharper the picture. The cheapest phones with smaller diagonals have HD resolutions. Full HD is the mid-range standard while high-end phones have finer resolutions. At the moment, 4K resolution is just an experiment on a few models. There are also other resolution values beyond those listed in the table.

Pixel Density

Display resolution is not everything. A 4K smartphone can still look more blurry than another smartphone with only Full HD. The difference here lies in the pixel density of the display - this depends on not only the resolution but also the size of the screen and the selected technology and processing. It is given in ppi (pixels per inch) and usually means that the higher the value, the sharper the image. For phones, this value averages around 350-400 ppi.

Display frequency

In recent months, one computer trend has been introduced to smartphones. We are talking about an increased refresh rate. The refresh rate is a value that indicates how many times per second the phone display is able to display new information. Until recently, the classic 60Hz panels were used (that's why the videos are mostly in 60 FPS, the displays could not handle more anyway).

Today, however, we encounter much higher values. Mid-range phones also have a 90Hz panel, while the top models reach up to 120 or even 144 Hz. You'll appreciate increased refresh rates everywhere, from simply browsing the interface to playing games or surfing the Internet. Initially, their problem was increased consumption, but today manufacturers are using adaptive refresh rates. Depending on the situation, it can vary from 1 Hz up to the maximum value to save energy.

Flexible display

Flexible displays are becoming an increasingly hot topic. Many manufacturers are starting to include this technology and each of them handles it a little differently. For example, the flexible Samsung Galaxy Z Fold2 5G bets on its book-style opening, while the Samsung Galaxy Z Flip and Motorola Razr are modern clamshells. Xiaomi released a bizarre prototype called the Mi Mix Alpha, which is literally all display. However, it is not available to the general public.

Every smartphone has its own memory. When choosing a phone, it is one of the most important parameters to consider. The larger the memory size, the faster and easier will it be to handle more operations at a time.

How many GB of memory do I need?

• 1-2GB - only seen in the cheapest and older smartphones and is usually not enough for today's apps. The system often freezes and does not respond under heavy load.

• 3-4GB - this is now considered a standard. 3 to 4GB of memory is enough for casual web browsing, listening to music, and playing games.

• 6-8GB - the regular value of mid-range smartphones, but also some flagship models. It ensures quick reaction times even during more demanding use.

• 12GB and more – a capacity found only in some flagships and leading gaming phones. It reliably banishes all nightmares about lagging, even when performing more demanding tasks or playing the most demanding games.

Processor cores

The most important part of the processor that is responsible for all computational operations. In smartphones, the number of cores usually ranges from 4 to 8, the more cores the better. Multiple cores work better between each other to shorten the processing time.

Processor frequency (clock)

Frequency indicates the number of instructions the processor can perform in 1 second. It is indicated in GHz. Higher frequencies increase CPU performance. Common frequency values range from 1.6GHz to 2GHz.

Processor model specification

This is the only indication that can help you predict the performance of your phone after searching for reviews and benchmarks. For example, a modern quad-core chip may be more powerful than an outdated eight-core.

Artificial Intelligence

With the latest high-end models, you may come across phones with artificial intelligence features. What is it all about? Maybe the phone's processor has a processing unit or an extra piece of code that makes it easy to take photos or save battery power. You can also experience artificial intelligence with virtual assistants like Google Assistant (Google), Alexa (Amazon), Siri (Apple), Bixby (Samsung), and so on. Smart algorithms are discussed in detail in AI - Artificial Intelligence (EVERYTHING YOU NEED TO KNOW).

Best-known manufacturers

Qualcomm
Their processors and graphics accelerators are particularly praised for their multitasking capability and gaming performance. The company has been manufacturing processors since 2005 and has gone through a long history of mobile engineering. Their Snapdragon processors are also used on flagships of the largest manufacturers, such as Google Pixel, Xiaomi Mi, or some of the Samsung Galaxy S model variants.

• Snapdragon - a CPU unit performance class specification. The series is marked with numbers: S200, S400, S600, S800. The first number marks the processor range and the second the processor model. The higher the number, the more powerful the processor. A graphics accelerator is also part of the processor.

• Cortex – a designation of individual processor cores. The most powerful ones include the Cortex A78 with 2.4 GHz, or the new Prime X series with the Corex X1. That one has a frequency of up to 2.84 GHz.
  

• Adreno - graphics accelerators that have a similar function to graphic cards in notebooks and computer desktops.

Apple
Apple keeps its processors in check and bets on smooth cooperation with the software.

• Apple A – a designation of processors in phones and tablets. In the iPhone 12, there is the Apple A14 Bionic chipset.
• Apple M – a series of processors that power desktop computers - the (MacBook, iMac, Mac mini) and since Spring 2021 also the iPad Pro. It works with the same architecture as conventional mobile processors, and it is speculated that Apple may implement them in the iPhone over time.

Samsung
The Korean electronics company has kept up with the competition and makes the processors that are used in their flagship mobile phones. It often mixes them with Qualcomm's processors, depending on the market the phone is made for.

• Exynos - a key range of octa-core processors by Samsung. Due to the advanced graphics chip, they are capable of being used for playing 3D games and processing a 4k UHD resolution.

MediaTek
The Taiwanese processor maker MediaTek is one of Qualcomm's main competitors. In its portfolio, it has everything through low-cost processors, mid-range chips, futuristic X-series - which reaches up to 3GHz. It boasts plenty of original features such as the patented MiraVision. These processors are very popular with Chinese manufacturers - most notably Xiaomi and Meizu.

• Helio - the most recent pride of this company. The MediaTek Helio processors combine the best of all previous generations. The manufacturer calls it the processor of the future.

HiSilicon
A Chinese company owned by Huawei. It is the largest printed circuit manufacturer on the Chinese market and has a great background for the development of new technologies. Unlike other Asian manufacturers, it does not increase performance by the number of computational cores but improves the core itself.

• Kirin 900 - the latest range of mobile processors used almost exclusively in Huawei and Honor smartphones and tablets.

nVidia
A well-known graphics card player started manufacturing mobile processors a few years ago and is certainly not behind the competition. nVidia processors excel primarily due to their performance in games. The state-of-the-art Tegra X1 is a quad-core chipset with a 256-pixel graphics unit and is therefore used in the Nvidia SHIELD Android TV portable game console.

• Tegra K1 - a processor used in many different mobile phones, or the Nvidia SHIELD tablet that can be used for computer games such as Half-Life or Knights of the Old Republic.

Battery life is measured in mAh (milliamp hours). The higher the number, the greater the capacity. The standard battery capacity for an entire day's battery life is approximately 4,500mAh. Values of 5,000mAh or more can be considered as an above-average battery that will provide good battery life from a single charge.

However, you should consider other factors that may affect the rate of discharge, such as display size, processor performance, and the use of data functions. To make battery life comparisons between phones as objective as possible, a laboratory-tested stand-by time is given. This is the maximum amount of time that a phone can last from a single battery charge when it is on but not in active use.

Many phones support fast charging, which means nothing more than charging the phone quickly. We can consider a value of 15 W and more as fast charging, but some mobile phones also offer 65W charging. It can charge the battery in a few dozens of minutes.

With more expensive phones, you may encounter wireless charging. This comes in handy if you don't want to constantly look for cables to plug in or you want to use a dock to simultaneously charge your smartphone and smartwatch.  Nowadays, several brands support wireless charging and more and more are following suit. Wireless power banks, such as Samsung Wireless Battery Packs work on the same principle as classic docks and are growing in popularity. Read more about Wireless Charging.

Another feature that has recently emerged is reverse charging. This is a cool feature found on some phones that support conventional wireless charging. Reverse charging turns your phone into a wireless charger. You can recharge a friend's battery  on the go or recharge smart accessories. Reverse charging is currently supported by the Samsung Galaxy S21 5G (and also the S21 Ultra and S21+) or the Xiaomi Mi 11.

Increasingly, the most important factor when choosing a mobile device is the built-in camera. Whether it's for nature, portraits, food, or selfies, the best camera phones are successfully replacing large-sized compacts.

Rear/front camera

Every smartphone and keypad phone comes with  a rear camera, whether standard, dual, triple, etc. The rear camera almost always has a higher resolution, aperture and a wider lens for nature and scenic photos. The front camera, which is often dual, is used for selfies.

Multiple-lens camera

Today, every modern smartphone has a camera with multiple lenses. In addition to the main (widescreen) lens, you will also find other types, with all of them excelling in something different. The most common lens types are:

• Ultra-wide - angle lenses - used to capture large areas (e.g. panoramas). They often have a viewing angle over 120°.
• Telephoto - good to have when shooting distant objects. Since zooming in with a wide-angle or ultra-wide-angle lens causes the picture to become blurry, telephoto lenses usually come equipped with optical zoom.
• Macro - great for capturing very close and small objects. Often used to photograph flowers or insects, for example.
• ToF - a depth camera, or its advanced ToF (time-of-flight) 3D variant, is used to detect different depth layers in photography. You can then easily separate and adjust them in a range of different ways. The popular bokeh effect is one well-known example.

Resolution

This is the number of pixels that the resulting photo will contain. It's not a sole factor that should determine the quality of the camera because the quality is primarily determined by the size of the sensor chip, and there is almost no difference between 14-28Mpx. Even some of the best manufacturers use lower resolution cameras – as seen in the iPhone 12 Pro (12 + 12 + 12 Mpx). The Samsung Galaxy S21 Ultra 5G on the other hand, uses a 108Mpx sensor.

Higher resolution is ideal for large image sizes, but the size of the sensor will be limited and the image quality will be lower in comparison to SLR cameras.

Luminance and aperture

The main camera parameter is not only megapixel (Mpx), but also the aperture. This is indicated by the letter "f". The number behind it indicates the loss of light when passing through the lens. The lower the number, the better the device can handle a lack of light, which is necessary in order to achieve sharp shots, not only in dim light. Greater luminosity can also create beautifully blurred backgrounds that we all love so much. The regular smartphone aperture size is around f/1.8 to f/2.4. The best devices offer f/1.5.

Video

Mobile phone cameras can also record high-definition videos, often with different features, such as slow-motion or a time lapse video. All phones record in Full HD resolution, with the more high-end models handling even 4K or 8K.

For video, an important parameter is the number of frames per second (fps). Typical values are 30 or 60 frames. If your phone handles Full HD video at 60 frames per second, the video will be smoother than Full HD at 30 frames per second. Slow-motion modes are a special case. They are able to capture video at very high frames (eg and 240 FPS).

HDR and scene modes

Because mobile cameras work more automatically than manually, they have lots of different modes for every occasion.

HDR is a feature that has always been used in photography and now finds its place in digital photography. It is a combination of photographs of various exposures used to produce a high-contrast image.

Panorama mode allows you to take very wide photos, such as the entire view from a lookout tower.

Portrait mode is for taking pictures of people. It uses the smallest aperture and blurs the background.

Macro mode is used when shooting small objects, such as flowers or insects.

Stabilisation

As you rarely use a tripod when taking photos with a mobile phone, image stabilisation is an integral part of each camera. It is divided into two categories - Electronic (EIS) and Optical (OIS). Cheaper models have electronic stability that only increases the ISO sensitivity to achieve a shorter shutter speed. The quality of resulting photos would sometimes be better if EIS was not applied at all. OIS, on the other hand, provides much better results, as it is built into the camera.Some phones use both technologies together, creating hybrid stabilisation .

Autofocus

Any decent camera should support autofocus. Better phones accelerate focusing at short distances using laser and arbitrary phase shift detection (PDAF). The best devices use a combination of both methods. For iPhone, the PDAF variation is called Focus Pixels.

ToF technology

ToF (Time-of-Flight) technologies, or sensors based on it, are very common in the latest phones. These are advanced depth sensors that measure the distance between themselves and objects in its field of view using light beams or ultrasound. They operate with a maximum error rate of just 1%, while conventional dual cameras have an error rate of up to 10%. This makes the ToF sensor more precise for creating a bokeh or focus effect. You can read more about Time-of-Flight sensors in this article.

Connectivity

• LTE/4G

Nowadays, no smartphone should be without LTE high-speed Internet support. However, you should be aware that some devices that support LTE do not understand Czech frequencies. Most of the local LTE network is built at a frequency of 800 MHz. In our technical parameters, you can usually find out whether the given device supports “Czech” LTE or not.

• 5G

The construction of 5G-based networks has begun worldwide, but is not yet a widespread standard for mobile networks. In the Czech Republic, 5G networks are only seen in specially designated test areas. In a few years, however, 5G could already become the norm, providing high data rates in towns, villages and remote parts of the country.

• GPS

Connecting to the Global Positioning System allows you to track your position on maps anywhere on Earth with an accuracy of several meters.

• WiFi

Internet connection via WiFi wireless technology.

• Bluetooth

Provides wireless communication between your phone and other devices, such as wireless speakers and headphones. The higher the series, the higher the connection speed and the lower the power consumption.

• NFC

NFC is a way of communication between two electronic devices. It serves for both data and information transmission. It is referred to as a technology of the future and is now commonly used for mobile payments. In Europe, we use Google Pay, Apple Pay and many more. With NFC, you can pay with your phone just like you would with a contactless credit card.

• Infraport

Used to transmit data using infrared radiation. Today it is not used too much as it is being replaced by Bluetooth and NFC. However, it still finds its use with a variety of electronics, such as televisions, air conditioners, home music players, etc.

• USB-C/Lightning/Micro USB

Sockets designed for a data cable connection. The data cable is used to charge or connect the phone to the computer.

USB-C - a modern version of USB. Most new smartphones have it.

Lightning - connector exclusive for iPhones.

Micro USB - still the most common connector for cheap Android phones. However, it looks like they are on their way out as this connector is slow and unsymmetrical.

• USB OTG

Do you plan to connect additional peripherals to your mobile phone? Then you will appreciate the presence of the USB OTG (On-The-Go) standard, which will further expand the connectivity of your phone. With the help of a special USB-C/Micro USB to classic “large” USB connection, you can connect external flash drives, hard drives (which may need additional power from a USB hub or an SD card reader. In certain situations, an Ethernet port or a wired keyboard or mouse may come in handy.

Sensors

• Barometer

An atmospheric pressure meter. A very useful gadget for smartphones.

• Light sensor

If you do not enjoy adjusting the screen brightness, the light sensor will do it for you.

• Motion sensor (accelerometer) and gyroscope

They monitor the movement and position of the phone. They are particularly used in the gaming industry, but can also have uses in everyday life, such as a mobile spirit level.

• Magnetic compass

It is used to determine cardinal points by the Earth's magnetic field.

• Proximity sensor

A very important sensor for every smartphone. When the phone is too close to your face during a call, the screen locks to prevent you from ending your call in error.

It is important, especially when buying phones without a memory card slot, to be careful and choose an option with a slightly larger memory. Bear in mind that the phone's operating system memory size is not included. So, if you buy a device with 16GB of memory, take into account that the average operating system occupies approximately 4-5GB of free space, leaving you just 11-12GB for your data. Since each manufacturer pre-installs different apps in their phones and uses their own graphical superstructures, the available storage for Android phones may vary between models and manufacturers.

The following memory size variants are offered on the market:

• Up to 16GB - for light users. Capacity holds a few applications.
• 32GB - for a few dozen applications and common use.
• 64GB - Store dozens of apps, games or music albums, several movies. This will be enough to do the trick for most regular users.
• 128GB - Store hundreds of apps, games and dozens of movies. Also suitable for intensive use.
• 256GB - Stores dozens of movies, games and applications to satisfy demanding users.
• 512GB to 1TB - these capacities are suitable for those who take a lot of photos, shoot 4K videos or use hundreds of large apps.

Tip: If your phone has low storage, you can help by removing all your backed up photos (e.g. in Google Photos) from your phone. You won't lose them, they'll always be available online, but they won't take up space on your mobile.

The material used to make your phone plays an important role in its appearance, durability and price.

• Plastic - all-plastic phones are relatively fragile and are normally the cheapest models. Plastic is also often used for camera lenses.
• Aluminium - pricier premium phones are primarily constructed from aluminium alloys. You may see combinations of aluminium and plastic or polycarbonate with a machined surface in mid-range models.
• Glass - a material used mainly in premium telephones to design the back cover.
• Stainless steel - a material sometimes used for frames as can be seen on the iPhone 12 Pro and Pro Max.

Fingerprint reader and facial recognition

If you're worried about your private information and files on your mobile phone, these features provide solid security. The standard location of a fingerprint reader is either on the back of the device, at the front, below the display, or directly integrated into the display.

AI Assistant

A handy feature built into any operating system. It can find the nearest restaurant for you or dial the contact you specify. The AI assistant in iOS is called Siri, while Google named its own Google Assistant.

Notification LED

Customise your phone's LED notification colours. Definitely a useful feature for  a smartphone! However, new phones use it less and less and you are unlikely to find it on a 2020 smartphone.

FM Radio

Most phones can use your headphones as a radio signal receiver, so you can tune in to your favourite station even when you are without an Internet connection.

Dual SIM

Telephones with the ability to use two SIM cards at one time are called Dual SIM. On one card you can have a voice tariff and a data card on the other, or you can use the services of two operators at the same time. A large number of phones allows the use of data services in only one of the SIM card slots. Dual SIM mobile phones are manufactured in both keypad and touch-screen versions.

eSIM

Thanks to eSIM (embedded SIM), you no longer need to own a physical SIM card and insert it into your phone. You won't have to ensure you choose a SIM, micro SIM or nano-SIM. The built-in chip in the phone, which replaces a conventional SIM card, allows you to enable any phone number by simply playing the eSIM profile over the data network of your operator. However, in the case of multiple eSIM profiles, only one of them can be used (for the time being).

Increased resistance

You can subject phones with increased resistance to some moisture or dust without damaging them. The level of resistance is usually indicated by the degree of protection, e.g. IP67 or IP68. The first number (6) indicates resistance to dust penetration and the second (here 7 or 8) to water. You can immerse an IP67 phone in water for half an hour at depths up to one metre without causing it harm. Rain won't damage it either. The crash resistance required for outdoor and sports activities is judged best by the rubber bumpers on the body of the phone.

Desktop mode

If you work with your mobile phone frequently on the go, have a monitor and require a portable PC-like workstation, you will love desktop mode. Selected phones, especially from the higher series with sufficient performance, have the ability to connect to your monitor, keyboard, mouse and other peripherals using a special hub. This gives you some desktop computer functionality that uses the power of your mobile phone. Examples include the Samsung DeX Station on their flagship S and Note series, and Desktop Mode on Huawei Mate models.

The question of Google services has only recently become relevant for Android smartphones, due to the conflict between the USA and China. Huawei has been banned from using Google services on its phones. So the new Huawei phones with new processors must be equipped with their own services. Currently, there are two options for Android phones:

• Google Mobile Services – the popular collection of all Google applications, including the Play Store. You will find GMS on the majority of Android smartphones.
• Huawei Mobile Services – a platform that doesn't allow the use of Google applications or the Play Store. Huawei is replacing these applications with its own ecosystem. You can read more in the article about HMS, where we tested these services. Huawei Mobile Services can be found on all new (approximately since 2020) Huawei smartphones.