We previously reviewed the Motorola Edge S, the first phone with the Snapdragon 870 chip. It’s possible that you were not quite satisfied with its overall performance of that phone. At the time, it was the only Snapdragon 870 phone launched in the market, so you didn’t have a choice. But now Redmi gives you a brand new option — the Redmi K40. Without further ado, let’s see how Redmi’s breakout model, the K40, performs in real life.

Redmi K40 Review: Design

The Redmi K40 comes in a regular-sized box. The charger and cable that disappeared from Mi 11’s box reappear in the K40 box. A 33w charger is included, and we’ll talk about the charging part later. 

At first glance itself, you realize that the K40 is much more refined than the K30. It weighs only 196g and is 7.8mm thick. The whole back is a continuation of the Mi 11 design. The camera module is elongated and the elements are distributed more evenly. This makes the back look much better than its predecessor. The red and blue gradient color is the main color of the K40. It refracts blue and red in different lights. While this is not the first time we have seen this color, if you are a person who likes a design that stands out, you will definitely like it. 

The side fingerprint sensor embedded into the power button is a bit raised. This differentiates the phone from the previous side fingerprint recognition phones which featured a sensor that was situated in a groove on the side. The advantage is that it is more integrated into the frame and looks like a normal power button. And this makes it easier to press with your finger. Overall, the design of the K40 is a definite improvement. It’s even better looking than the Mi 11. This should be the first time that Redmi is on par with Xiaomi in terms of design. 

You can check out the design of the Redmi K40 and K40 Pro in more detail in our hands-on article. 

Redmi K40 Review: Display Experience

This year the K40 series uses a flat E4, 1080p, 120hz refresh rate OLED screen. The screen is one of the main selling points of the K40 series. Featuring 1300 nits of peak brightness and a 5,000,000:1 contrast ratio, while consuming 15% less power, the performance is truly outstanding. And with support for a three-finger 360hz touch sampling rate, multi-finger control should be more responsive than other phones. But the improvement in experience is more obvious to the user perception than the improvement in parameters. 

There are two obvious points of improvement in the screen experience of the K40. First one is the tiny 2.76mm hole-punch and the second one is the “Adaptive Color display”. This is one of the smallest hole-punch we’ve seen, allowing you to almost ignore the front camera and immerse yourself in the joy of video. As for “Adaptive Colors”, it is not a strange concept for iPhone users. It adjusts the color temperature of the screen to the color temperature of the ambient light. This feature can help reduce eye strain. 

Apart from the plastic frame and the wide bezels, the screen for the price point is excellent.

Redmi K40 Review: Performance & Gaming

As you might have already seen in our Motorola Edge S review, the Snapdragon 870 is a very well-balanced chip. As a long-time Qualcomm customer, will Redmi be able to tune the Snapdragon 870 any better?

 Let’s look at the regular Benchmark results first. 

The phone scores the following in benchmark tests: AnTuTu score is 662,201, 3DMark score is 4192, and GeekBench 5’s single-core score is 1034, and multi-core score is 3485. We can see that the K40’s peak performance tuning is similar to the Edge S. 

Next, let’s look at the tuning optimization for sustained performance output. In the Genshin Impact half-hour stress test the phone ran at 50.45fps, a little higher than the Edge S. Although judging from the frame rate curve, Redmi’s K40 and Edge S’ gaming performance look about the same. But looking at the frequency of lag, the K40 seems to be more consistently tuned.

Now let’s take a look at the BrightRidge 20 minute test, in which the K40 got an average of 42 fps. This is lower than the Edge S. And there were a few times when the frame rate was only about 20 frames after down throttling. The experience was not very good. So it looks like for games that were optimized for the Redmi model, the phone offers a better gaming experience than the Edge S. And the temperature never went above 50℃. But if there were no targeted optimizations, the gaming experience would be inferior to the Edge S.

Redmi K40 Review: Camera Performance

Given its price segment, we knew the cameras were going to be average. Let’s see how good it is at taking photos.

Please note that the below galleries feature the full-size samples from the K40 and a few samples from the K40 Pro for comparison. If you want to check out the comparison with Motorola Edge S, please watch our video review.

Main Camera

K40’s main camera is the IMX582 sensor introduced the year before and there is no optical stabilization. The ultra-wide-angle sensor is 8MP, and there’s a 5MP telephoto macro lens of the same type as the Mi 11. 

In real life, the K40’s primary camera underexposed samples in daylight conditions. Dynamic range is also not good, with serious loss of detail in dark areas. Colors are also not vibrant enough. The resolution is also inadequate.  Apart from the slightly better control of the purple-fringing issue, the K40 loses out in all daytime scenes. 

Night Camera Performance 

At night the K40’s exposure returns to normal. Although the highlights still spill over, there is much less noise than the edge s with almost the same resolution. There is also more detail in the dark areas than in the Edge S. This was applicable with Night mode on as well. Although the Edge s has improved its exposure in extreme dark lighting conditions, the noise is still not reduced. So the night time camera performance is a small victory for the K40.

Ultra Wide Angle Camera

Both phones’ ultra-wide lenses perform the same as the main camera in daylight. The K40 didn’t do well and was defeated in this department. Since the results were the same, I won’t repeat myself. At night the K40 achieves another comeback. It wins across the board, except for the small range of highlight suppression, which sometimes was not good. If you turn on night mode, the gap will widen even more.

Macro Shooting

The K40 uses a separate special lens for macro shooting. So the focus distance is much closer than the Edge s. This is why the results are particularly impressive. As for the video, I just want to remind you that the K40 does not have 6K videos on its main camera. 4K only supports 30fps. Both the Edge S and the K40 only support up to 1080p 30fps from its ultra-wide camera.

Redmi K40 Review: Battery Life 

The K40 comes with a 4520mAh battery. After our tests, half an hour of Tiktok and half an hour of 1080p internet video both use only 5% of the power. 30 minutes on the Genshin Impact consumes 18%. 20 minutes on the BrightRidge consumes 20%. This battery optimization is still good. 

Although the K40 is still using 33w of charging, they’ve optimized it a lot this time. It charges to 69% in half an hour and can be fully charged in 54 minutes. So this is faster than many other brands’ 40w charging. So you don’t have to worry at all that the 33w of the k40 is not enough.

Redmi K40 Review: Conclusion

To conclude, if you’re looking for a phone with high performance, low heating, and not so demanding camera, the K40 is perfectly suited for you. There are even a few surprises, such as the excellent E4 screen and the sophisticated design. Given its drawbacks, it’s not the best phone but it will be the most comfortable phone you can buy in this price range, at least for now. 

There have been a lot of new phones recently, so the competition will definitely get tougher in the coming months.

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