Xiaomi is among the first makers to introduce the tall display on a budget smartphone. The 18:9 display is 5.99" big on the Redmi S2, which is a bit of a stretch for its 720x1440 resolution. Still, at 269ppi density we saw no pixelization, and while the screen won't top any charts, it is quite enough for the class.
The Redmi S2 display has a maximum brightness of 500 nits, but its black levels aren't that deep, which led to an average contrast ratio of 1000:1. But that's the contrast Xiaomi is promising, and apparently, it has delivered.
Display test
100% brightness
Black, cd/m2
White, cd/m2
Contrast ratio
Xiaomi Redmi S2 (Y2)
0.47
504
1072
Xiaomi Redmi Note 5A (Y1)
0.315
527
1673
Xiaomi Redmi 5 Plus
0.548
555
1013
Xiaomi Redmi 5
0.378
503
1331
Oppo Realme 1
0.35
423
1209
Xiaomi Mi A1
0.351
551
1570
Samsung Galaxy J5 (2017)
0
326
∞
vivo V7+
0.289
515
1782
Huawei P20 Lite
0.27
482
1785
Sunlight legibility is nothing to phone home about, although its score is still respectable especially for a budget phone. In real-world terms, the handset remains perfectly usable outdoors. Just don't angle the sun straight at it.
Sunlight contrast ratio
Apple iPhone X 5.013
OnePlus 5T 4.789
Samsung Galaxy S8 4.768
Samsung Galaxy S8+ 4.658
Samsung Galaxy S9 4.63
Samsung Galaxy S6 edge+ 4.615
Samsung Galaxy S9+ 4.537
Motorola Moto Z2 Play 4.459
Oppo R11 4.454
Samsung Galaxy S7 edge 4.439
OnePlus 3 4.424
Samsung Galaxy S7 4.376
HTC One A9 4.274
Oppo R15 Pro 4.251
Samsung Galaxy Note7 4.247
Samsung Galaxy A3 4.241
Nokia 8 4.239
Google Pixel 2 XL (pre-update) 4.234
OnePlus 3T 4.232
Google Pixel XL 4.164
ZTE Axon 7 4.154
Samsung Galaxy Note8 4.148
Meizu Pro 7 Plus 4.147
Samsung Galaxy S6 edge 4.124
Samsung Galaxy A7 (2017) 4.124
Huawei Mate 10 Pro (normal) 4.096
Samsung Galaxy Note5 4.09
Huawei P20 Pro 4.087
Nokia 6 (2018) 4.052
Google Pixel 2 (pre-update) 4.023
LG V30 4.022
Huawei Nexus 6P 4.019
Samsung Galaxy J7 Pro 3.998
OnePlus X 3.983
Vivo Xplay5 Elite 3.983
Apple iPhone 7 3.964
Oppo R7s 3.964
Apple iPhone 8 (True Tone) 3.957
Huawei P9 Plus 3.956
Meizu Pro 6 Plus 3.935
Lenovo Moto Z 3.931
Samsung Galaxy A7 (2016) 3.918
OnePlus 5 3.914
Samsung Galaxy C5 3.911
Samsung Galaxy C7 3.896
Samsung Galaxy A5 3.895
Samsung Galaxy J7 outdoor 3.879
Samsung Galaxy J2 outdoor 3.873
Motorola Moto G6 Plus 3.865
Samsung Galaxy A8 3.859
Samsung Galaxy A8 (2018) 3.842
Sony Xperia XZs 3.818
Samsung Galaxy A9 (2016) 3.817
Motorola Moto X (2014) 3.816
Samsung Galaxy J7 (2017) 3.812
Samsung Galaxy A5 (2017) 3.804
Samsung Galaxy J7 (2016) outdoor mode 3.802
Xiaomi Redmi Pro 3.798
LG V20 Max auto 3.798
Sony Xperia XZ 3.795
Samsung Galaxy A5 (2016) 3.789
Apple iPhone 6s 3.783
Meizu Pro 5 3.781
Microsoft Lumia 650 3.772
Xiaomi Mi 6 3.767
Sony Xperia XZ1 3.765
Samsung Galaxy J7 (2016) 3.756
Nokia 8 Sirocco 3.745
Sony Xperia XZ1 Compact 3.729
Apple iPhone 8 Plus (True Tone) 3.725
Oppo F1 Plus 3.709
Vivo X5Pro 3.706
Samsung Galaxy A3 (2017) 3.688
Huawei P20 3.683
Apple iPhone SE 3.681
Huawei Mate 9 3.68
Samsung Galaxy A7 3.679
Sony Xperia XZ2 Compact 3.675
Meizu PRO 6 3.659
BlackBerry Priv 3.645
Sony Xperia XA1 Ultra 3.597
Apple iPhone 7 Plus 3.588
Sony Xperia XZ2 3.58
LG G6 3.556
Apple iPhone 6s Plus 3.53
Motorola Moto Z Play 3.526
Samsung Galaxy J3 (2016) 3.523
Samsung Galaxy J3 (2016) outdoor mode 3.523
Acer Jade Primo 3.521
Microsoft Lumia 950 3.512
Oppo R7 Plus 3.499
Nokia 7 plus 3.479
nubia Z11 3.466
Huawei P10 Plus 3.456
HTC U Ultra 3.453
Motorola Moto G6 3.448
Sony Xperia XA2 Ultra 3.445
Samsung Galaxy J7 3.422
Motorola Moto G6 Play 3.419
Meizu MX5 3.416
LG V20 3.402
Samsung Galaxy A6 (2018) 3.397
Xiaomi Redmi Note 5 AI Dual Camera 3.393
Huawei P10 3.379
Samsung Galaxy J5 (2016) 3.378
Oppo R9s 3.352
Honor 8 Pro 3.341
Oppo F7 3.333
Oppo R7 3.32
Lenovo P2 3.316
Archos Diamond Omega 3.305
Honor 9 3.289
Xiaomi Mi 5s 3.276
Nokia 5 3.261
Nokia 6 (Chinese version) 3.244
Nokia 6 (Global version) 3.238
Samsung Galaxy J2 3.235
Sony Xperia X Performance 3.234
Xiaomi Mi Note 2 3.228
Motorola Moto X Play 3.222
Oppo F3 Plus 3.218
Huawei Mate 9 Pro 3.206
Huawei P9 3.195
Xiaomi Mi Mix 2 3.19
ZTE Nubia Z17 3.159
Oppo R11s 3.153
Lenovo Vibe Shot 3.113
HTC U11 Life 3.108
Motorola Moto X Force 3.105
LG Nexus 5X 3.092
HTC U11 3.089
Xiaomi Redmi S2 (Y2) 3.077
Huawei Mate S 3.073
Microsoft Lumia 640 XL 3.065
Apple iPhone 6 Plus 3.023
Asus Zenfone 4 ZE554KL 3.019
Sony Xperia XA1 3.012
Motorola Moto X4 3.012
Sony Xperia L1 2.994
Sony Xperia X 2.989
LG Q6 2.987
Huawei P10 Lite 2.974
Samsung Galaxy Note 2.97
Huawei P20 Lite 2.952
Xiaomi Redmi 5 2.951
Huawei Mate 8 2.949
Sony Xperia XA2 2.938
Oppo Realme 1 2.932
Xiaomi Redmi 4 2.92
Xiaomi Redmi 3S 2.913
Xiaomi Redmi 5 Plus 2.913
Sony Xperia XA Ultra 2.906
LG G5 2.905
Huawei Honor View 10 2.896
Xiaomi Redmi 3s Prime 2.893
Xiaomi Mi 5s Plus 2.884
Sony Xperia XZ Premium (sRGB) 2.877
Sony Xperia XZ Premium 2.877
Sony Xperia Z5 2.876
Nokia 3 2.871
Microsoft Lumia 550 2.851
Lenovo Moto M 2.813
Xiaomi Redmi 3 Pro 2.803
Sony Xperia Z5 compact 2.784
Honor 10 (Vivid) 2.757
Nokia 2 2.752
Meizu MX6 2.751
LG V10 2.744
Huawei Mate 10 (normal) 2.742
Motorola Moto G5S Plus 2.737
Xiaomi Redmi 3 2.735
Huawei Honor 7X 2.734
Xiaomi Redmi Note 4 (S625) 2.714
Meizu M5 2.71
Sony Xperia M5 2.69
Xiaomi Mi A1 2.689
Huawei P9 Lite 2.679
Xiaomi Redmi 4 Prime 2.679
vivo V7+ 2.671
Vivo V3Max 2.659
Xiaomi Mi Mix 2.658
Huawei Mate 10 Lite 2.654
Oppo F5 2.653
Doogee Mix 2.642
Xiaomi Mi 4i 2.641
Xiaomi Redmi 4a 2.635
Xiaomi Mi 5X (Standard) 2.616
Sony Xperia XA 2.609
Motorola Moto G4 Plus (max auto) 2.582
Motorola Moto G4 Plus 2.582
Meizu M5s 2.58
Xiaomi Mi 4c 2.574
LeEco Le Max 2 2.567
Asus Zenfone 3 ZE552KL 2.563
Huawei P Smart 2.563
Microsoft Lumia 640 2.563
Xiaomi Mi Max 2 2.561
Xiaomi Redmi Note 5A (Y1) 2.556
HTC U11+ 2.556
Lenovo K6 Note 2.544
Lenovo Moto G4 2.544
Oppo F1 2.528
Sony Xperia Z5 Premium 2.525
Huawei Honor 7 Lite / Honor 5c 2.506
Sony Xperia M4 Aqua 2.503
BlackBerry Motion 2.494
Oppo F1s 2.481
Motorola Moto G 2.477
Lenovo Vibe K5 Plus 2.473
Huawei G8 2.471
Huawei nova 2.467
Sony Xperia Z 2.462
Lenovo Vibe K5 2.459
Meizu m3 max 2.447
Xiaomi Mi 4 2.424
Xiaomi Mi 5X (Auto) 2.417
HTC 10 evo 2.407
Huawei Honor 7 2.406
Vivo V7 2.404
Sony Xperia E5 2.386
ZUK Z1 by Lenovo 2.382
HTC 10 2.378
Oppo F3 2.376
vivo V5 Plus 2.371
Meizu m1 note 2.362
Huawei nova plus 2.329
Razer Phone 2.328
HTC One E9+ 2.305
Alcatel One Touch Hero 2.272
Sony Xperia L2 2.266
Lenovo Vibe K4 Note 2.254
HTC U11+ (EU) 2.253
Sony Xperia C5 Ultra 2.253
Xiaomi Redmi Note 3 (MediaTek) 2.249
Sony Xperia C4 Dual 2.235
Xiaomi Mi Note 2.234
Motorola Moto G (2014) 2.233
LG Nexus 5 2.228
Huawei P8 2.196
Meizu M5 Note 2.189
Huawei Honor 6 2.169
Xiaomi Redmi Note 2 2.166
OnePlus Two 2.165
HTC One X 2.158
LG Aka 2.145
Xiaomi Redmi Note 4 (X20) 2.145
Archos 50 Diamond 2.134
Xiaomi Redmi Note 2.119
Xiaomi Mi 4S 2.095
Acer Liquid X2 2.084
Huawei P8lite 2.078
vivo V5 2.059
Moto G 3rd gen max manual 2.026
Xiaomi Mi 3 2.001
Xiaomi Mi Max 1.996
Sony Xperia E4g 1.972
OnePlus One 1.961
Sony Xperia Z2 1.944
Meizu m3 note 1.923
BlackBerry Leap 1.892
Meizu m2 note 1.892
HTC Butterfly 1.873
Sony Xperia Z1 Compact 1.772
ZTE Nubia Z9 mini 1.759
Sony Xperia U 1.758
Asus Zenfone Selfie 1.68
Motorola Moto E (2nd Gen) 1.675
ZTE Nubia Z9 1.659
Jolla Jolla 1.605
Motorola Moto E 1.545
Sony Xperia M 1.473
Sony Xperia L 1.351
Xiaomi Redmi 2 1.311
HTC Desire C 1.3
Nokia X 1.291
Meizu MX 1.221
Sony Xperia E 1.215
The default (Standard with Auto setting) color rendering is average - the screen offers mostly accurate colors, but it looks a bit bluish, and the representation of the white color is way colder than it should be (DeltaE of 14). The overall color rendering out of the box worked out to an average DeltaE of 7.6, which is fine if you are okay with the cooler looking whites.
You can switch from Auto contrast to Standard and get rid of the blue tint. This mode will give you much more accurate color presentation with an average deltaE of 3.6 and a maximum deviation of 7 at point white.
Battery life
The Redmi S2 is powered by a 3,080mAh sealed battery - the same as on the Y1. It supports regular 5V/2A charging, which restores about 30% of the battery in 30 minutes of charging from zero. Not exactly fast, but expected for the price segment.
The S2 has the same energy-efficient Snapdragon 625 chip as many other Redmi phones, so we expected the S2 (or Y2) to do better than the Y1 (S435) in spite of the larger screen.
And it did - the Redmi S2 easily scored an excellent result in our battery test with a 92-hour Endurance rating. It did a great job in all tested scenarios - video playback, calls, web browsing and stand-by performance. That's a significant improvement over the Y1 with its 74h rating.
Our endurance rating denotes how long a single battery charge will last you if you use the Redmi S2 for an hour each of telephony, web browsing, and video playback daily. We've established this usage pattern, so our battery results are comparable across devices in the most common day-to-day tasks. The battery testing procedure is described in detail in case you're interested in the nitty-gritties. You can also check out our complete battery test table, where you can see how all of the smartphones we've tested will compare under your own typical use.
Loudspeaker
The Redmi S2 has a single bottom-firing speaker at its disposal. It scored a Very Good mark in our loudness test, but its output is not that rich to impress. Still, we've seen plenty of worse, so we are fine with what we got for this class.
Speakerphone test
Voice, dB
Pink noise/ Music, dB
Ringing phone, dB
Overall score
Xiaomi Redmi Note 4
64.2
67.2
76.9
Good
LG Q6
67.0
69.3
76.1
Good
vivo v7+
66.5
73.1
79.6
Very Good
Xiaomi Redmi S2 (Y2)
68.1
69.6
82.2
Very Good
Huawei P20 Lite
66.3
71.5
84.9
Very Good
Oppo Realme 1
64.8
70.5
89.9
Very Good
Xiaomi Redmi Note 5A
68.4
72.3
86.2
Very Good
Xiaomi Redmi 5 Plus
71.1
72.7
87.7
Excellent
Xiaomi Mi A1
74.0
73.9
90.4
Excellent
Audio quality
The Xiaomi Redmi S2 pulled off a beautiful performance in our audio output quality test. It was very loud both with an active external amplifier and with our standard headphones set and its accuracy was basically flawless.
In fact, we could barely register any change when the headphones were plugged in, which is a real rarity among smartphones. And when you consider that it's not even a flagship, but a mere mid-ranger, this is a properly impressive performance.
Test
Frequency response
Noise level
Dynamic range
THD
IMD + Noise
Stereo crosstalk
Xiaomi Redmi S2
+0.02, -0.05
-90.3
90.2
0.0015
0.015
-93.1
Xiaomi Redmi S2 (headphones)
+0.02, -0.06
-93.3
93.2
0.0034
0.056
-82.5
Xiaomi Redmi Note 5 AI Dual Camera
+0.04, -0.05
-89.4
89.4
0.0018
0.016
-90.5
Xiaomi Redmi Note 5 AI Dual Camera (headphones)
+0.13, -0.00
-90.4
90.4
0.0018
0.041
-80.8
Motorola Moto G6 Plus
+0.00, -0.03
-93.6
93.5
0.0050
0.011
-94.6
Motorola Moto G6 Plus (headphones)
+0.02, -0.02
-93.5
93.4
0.0067
0.033
-81.0
Oppo F7
+0.01, -0.10
-92.5
92.7
0.0019
0.0077
-91.2
Oppo F7 (headphones)
+0.50, -0.20
-91.4
91.8
0.0079
0.402
-51.5
Nokia 6 (2018)
+0.10, -0.20
-37.5
80.4
0.0018
4.735
-93.3
Nokia 6 (2018) (headphones)
+0.05, -0.03
-94.3
90.2
0.0027
0.019
-58.6
Nokia 7 Plus
+0.02, -0.31
-38.8
81.7
0.0013
4.690
-95.9
Nokia 7 Plus (headphones)
+0.25, -0.23
-93.3
90.4
0.0045
0.227
-53.9
Honor View 10
+0.02, -0.01
-92.6
92.6
0.0021
0.012
-94.4
Honor View 10 (headphones)
+0.17, -0.03
-92.0
92.1
0.0023
0.092
-52.8
Xiaomi Redmi S2 frequency response
You can learn more about the tested parameters and the whole testing process here.
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