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How we test mobile phones

By Oli McKean

Find out more about our mobile phone tests, and why you can trust our independent mobile phone reviews to unearth the best models on the market.

Put us to the test

Our Test Labs compare features and prices on a range of products. Try Which? to unlock our reviews. You'll instantly be able to compare our test scores, so you can make sure you don't get stuck with a Don't Buy.

We go further than any other organisation to find the best mobile phones on the market today. 

Each mobile phone we review goes through an assault course of technical lab tests and hands-on assessments by independent experts, to ensure we recommend only the cream of the crop.

Our reviews answer the most crucial questions about mobile phones:

  • Is the screen easy to read and detailed?
  • Do calls sound loud and clear?
  • Do the cameras take photos you'll be proud of?
  • How long does the battery last?
  • How good is the music player?
  • Should you buy it?

Find out which models deserve a place in your pocket - head to our mobile phone reviews.

Is the screen easy to read and detailed?

We scrutinise on-screen text and icons, to assess how clearly they appear. The best displays are clear and vibrant, and text is well-sized for trouble-free reading.

Our tests also cover whether it's easy to make out the screen in bright sunlight, or whether you'll have to really focus to send a text while walking through the park on a summer's day.

We also check whether you'll struggle understanding the display from any angle, or whether you'll need to hold the phone in direct line with your eyes every time you want to use it.

Do calls sound loud and clear?

To see whether a mobile phone is up to the job of allowing you a carefree natter to your friends and family, we test its call quality vs a BT home phone.

We don't test this only in a quiet room, but also make a call with a noisy café soundtrack playing in the background, to find out how it copes in a more challenging environment.

The track is played at 74dBA – that’s somewhere between the level of the average alarm clock and normal street noise. We listen to see whether you and the person on the other end of the line can be understood.

Some phones make it easy to have a clear catch-ups with your friends and relatives, whatever the environment. Unfortunately, some may leave you struggling to follow the flow of the conversation.

Do the phone's cameras take decent images?

We capture a variety of photos at long and close range so we can tell you if the main camera can take a decent landscape shot, as well as an up-close-and-personal profile. Our test photos feature a weird and wonderful range of objects, from a fluffy teddy bear to a wicker chair. These are used so our experts can assess whether the camera picks up texture and subtle detail.

We also examine how it copes in low light – which we affectionately refer to as the ‘pub shot’. And it’s only fair that we take a couple of photos with the front-facing camera, too, so we can tell you whether it’s any good at snapping selfies.

The best mobile phones take fantastic photos that rival those taken by a brilliant compact camera in normal light conditions. The worst, on the other hand, take low-resolution snaps that lack detail and good colour reproduction - essential ingredients for a terrific shot.

How long does the battery last? 

Nobody wants a phone that runs out of charge before the day is done, so we charge the battery up to full before timing how long it lasts when making continuous calls. We then charge it up all over again and time how long it lasts when browsing the web via 3G. These tough tests tell us whether it will go the distance or if you’ll be reaching for the charger before lunch.

There are huge differences between the best and worst smartphones for battery life. For instance, one of our Best Buys musters a jaw-dropping 31 hours of continuous calls before losing charge - while our lowest-scoring Don't Buy doesn't even achieve a paltry seven hours before giving up.

How good is the mobile phone's music player?

As many of us use our phones to listen to music, instead of carrying around a separate music player, we run a listening test to see what it’s like when playing your favourite tracks.

We use a pair of standard headphones (Apple earbuds) to play six tracks that represent a range of genres, from bass-heavy pop numbers such as Janet Jackson’s ‘Rhythm Nation’ to Rachmaninov’s Symphony no.2 - a true test of their ability to handle detail.

Should you buy it?

74%The score mobile phones need to earn our Best Buy recommendation

Each of the assessments described above contributes to a total test score we award to all mobile phones we review. The test score ensures you can see which phones are the best and worst, and how each compares to others. 

To calculate the test score, we focus on overall usability, including screen, battery life, processor power and call quality, and don’t take price into account.

The total score is made up of the following factors:

  • 25% battery
  • 15% ease of use
  • 15% camera
  • 10% call sound quality
  • 10% processor
  • 10% screen quality
  • 10% music and video
  • 5% build quality

A mobile phone needs 74% in our tests to earn our Best Buy recommendation. Mobile phones that score 45% or less are labelled Don’t Buys to make them easier to avoid.


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