Between the ScanWatch 2 and Watch S4, the ScanWatch 2 comes out ahead in battery life, while the Watch S4 wins on display size and weight. Overall, the ScanWatch 2 scores 72.6 and the Watch S4 scores 63.9 on our Mars Score.
Which should you buy?
The ScanWatch 2 is the clear pick on raw spec strength, leading by 8.7 points on the Mars Score. The margin is wide enough that the underdog only makes sense if its individual strengths line up with what you specifically need.
Pick the ScanWatch 2 if your top frustration with your current device is running out of charge before the day ends — endurance is the lead spec here. The biggest gaps in its favor are battery life.
Pick the Watch S4 if you carry the device everywhere and weight or thickness has been the deciding factor before. Its strongest claims are display size, weight, cellular, among others.
Both ship with comparable ecg, spo2, water resistance, so those specs don't separate the two — focus on the differences below.
Bottom line: the ScanWatch 2 is the safer default. The other model is the right choice only when its specific advantages line up with your priorities.
Why Withings - ScanWatch 2 wins
- ▲Battery life — 100.00% more. 720 h vs 360 h.
Why Xiaomi - Watch S4 wins
- ▲Display size — 126.98% more. 1.43 " vs 0.63 ".
- ▲Weight — 15.00 g less. 44 vs 59.
- ▲Has Cellular.
- ▲Peak brightness: 2200 nits vs 0 nits.
Spec comparison
Design
| Spec | Withings - ScanWatch 2 | Xiaomi - Watch S4 |
|---|---|---|
| Case size | 42 mm | 47 mmlead |
| Weight | 59 g | 44 glead |
| Case material | stainless steel | stainless steel |
| Water resistanceⓘ | 5 ATM | 5 ATM |
Display
| Spec | Withings - ScanWatch 2 | Xiaomi - Watch S4 |
|---|---|---|
| Display size | 0.63 " | 1.43 "lead |
| Always-on display | false | truelead |
| Peak brightnessⓘ | 0 nits | 2200 nitslead |
Health & Fitness
| Spec | Withings - ScanWatch 2 | Xiaomi - Watch S4 |
|---|---|---|
| ECG | true | true |
| SpO2 | true | true |
| Temperature sensor | true | true |
| Sleep tracking | true | true |
| Blood pressure | false | false |
Battery & Connectivity
| Spec | Withings - ScanWatch 2 | Xiaomi - Watch S4 |
|---|---|---|
| Battery life | 720 hlead | 360 h |
| GPS | false | truelead |
| Cellular | false | truelead |
| NFC | false | truelead |
| OS | Withings OSlead | HyperOS |
Frequently asked
Which has longer battery life, ScanWatch 2 or Watch S4?+
ScanWatch 2 lasts 720h vs 360h.
Do ScanWatch 2 or Watch S4 support ECG?+
Both support ECG.
Which has cellular, ScanWatch 2 or Watch S4?+
Watch S4 offers a cellular variant; ScanWatch 2 is Wi-Fi only.
Spec-level deep dives
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