Redmi K40 vs Redmi K90 Ultra
The Redmi K40 (2021) runs on the Qualcomm Snapdragon 870, while the Redmi K90 Ultra (2026) runs on the Qualcomm Snapdragon 8 Elite; estimated prices are $309 and $420. By overall MobileRank rating, the Redmi K90 Ultra leads — 73/100 vs 54/100 (a 19-point difference). Key differences: the Redmi K90 Ultra has the bigger battery (8550 mAh vs 4520); the main camera is 48 MP vs 50 MP; the Redmi K90 Ultra is faster in AnTuTu (3,119,308 vs 1,010,069); the Redmi K40 is noticeably lighter (196g vs 227g).
Redmi K40
Redmi K90 Ultra
- Lighter: 196g vs 227g
- Cheaper: $309 vs $420
- Better portability (64/100 vs 40/100)
- Higher AnTuTu: 3119308 vs 1010069
- Better Geekbench Single: 3041 vs 1298
- Better Geekbench Multi: 9494 vs 3520
- Bigger battery: 8550 vs 4520 mAh
- Faster charging: 100W vs 33W
- Better main camera: 50MP vs 48MP
- Higher refresh rate: 165Hz vs 120Hz
- Higher performance (92/100 vs 61/100)
- Better camera (37/100 vs 36/100)
- Longer battery life (78/100 vs 42/100)
- Better display (94/100 vs 79/100)
Comparing the Redmi K40 vs the Redmi K90 Ultra, the Redmi K90 Ultra scores 19 points higher (73/100 vs 54/100). In the "performance" category, the Redmi K90 Ultra leads (92/100 vs 61/100). In the "battery" category, the Redmi K90 Ultra leads (78/100 vs 42/100). In the "performance" category, the Redmi K90 Ultra significantly outperforms the Redmi K40 (92/100 vs 61/100). In the "display" category, the Redmi K90 Ultra notably outperforms the Redmi K40 (94/100 vs 79/100). In the "camera" category, the Redmi K90 Ultra and the Redmi K40 are nearly equal (37/100 vs 36/100). In the "battery" category, the Redmi K90 Ultra significantly outperforms the Redmi K40 (78/100 vs 42/100). In the "portability" category, the Redmi K40 notably outperforms the Redmi K90 Ultra (64/100 vs 40/100).
| Specification | Redmi K40 | Redmi K90 Ultra | |
|---|---|---|---|
| Processor | Qualcomm Snapdragon 870 | Qualcomm Snapdragon 8 Elite | |
| AnTuTu | 1010069 | 3119308 | |
| Geekbench Single | 1298 | 3041 | |
| Geekbench Multi | 3520 | 9494 | |
| Display | 6.7" AMOLED | 6.8" AMOLED | |
| Resolution | 2400x1080 | 1280x2772 | |
| Refresh rate | 120 Hz | 165 Hz | |
| Battery | 4520 mAh | 8550 mAh | |
| Charging | 33W | 100W | |
| Main camera | 48 MP | 50 MP | |
| Ultrawide | 8 MP | 8 MP | |
| Front camera | 20 MP | 20 MP | |
| RAM | 6GB / 8GB / 12GB | 12GB / 16GB | |
| Storage | 128GB / 256GB | 256GB / 512GB | |
| OS | Android 11 | Android 16 | |
| Brightness (peak) | — | 3500 nits | |
| NFC | — | yes | |
| Protection | — | IP68/IP69 | |
| Dimensions | — | 162.9×77.9×8.2 mm | |
| Weight | 196 g | 227 g | |
| Price | $309 | $420 |
Redmi K40
- Main: 48MP f/1.79
- Ultrawide: 8MP
- Front: 20MP
Redmi K90 Ultra
- Main: 50MP f/1.7
- Ultrawide: 8MP
- Front: 20MP
Redmi K40
- 6.7" AMOLED
- Resolution: 2400x1080
- Refresh rate: 120 Hz
Redmi K90 Ultra
- 6.8" AMOLED
- Resolution: 1280x2772
- Refresh rate: 165 Hz
Redmi K40
- 4520 mAh
- Wired: 33W
- Wireless charging: no data
Redmi K90 Ultra
- 8550 mAh
- Wired: 100W
- No wireless charging
We compared Redmi K40 and Redmi K90 Ultra, covering their specs and all relevant benchmarks.
Redmi K90 Ultra leads Redmi K40 by 67.6% in our overall performance rating.
Price difference: $111. Redmi K40 is cheaper by $111.
performance
In the "performance" category, the Redmi K90 Ultra significantly outperforms the Redmi K40 (92/100 vs 61/100).
display
In the "display" category, the Redmi K90 Ultra notably outperforms the Redmi K40 (94/100 vs 79/100).
camera
In the "camera" category, the Redmi K90 Ultra and the Redmi K40 are nearly equal (37/100 vs 36/100).
battery
In the "battery" category, the Redmi K90 Ultra significantly outperforms the Redmi K40 (78/100 vs 42/100).
portability
In the "portability" category, the Redmi K40 notably outperforms the Redmi K90 Ultra (64/100 vs 40/100).
Which is better: the Redmi K40 or the Redmi K90 Ultra?
The Redmi K90 Ultra is noticeably better than the Redmi K40 — the overall rating gap is 19 points.
What is the rating of the Redmi K40 and the Redmi K90 Ultra?
The Redmi K40 has a MobileRank rating of 54/100, the Redmi K90 Ultra — 73/100.
Which is more powerful: the Redmi K40 or the Redmi K90 Ultra?
The Redmi K90 Ultra leads on performance (92/100 vs 61/100).
Should you choose the Redmi K40 over the Redmi K90 Ultra?
The Redmi K40 is a better fit for active users. The Redmi K90 Ultra is a better fit for gamers and power users, those who care about battery life.