Between the OnePlus Watch 3 and Watch S4, the OnePlus Watch 3 comes out ahead in display size, while the Watch S4 wins on battery life and weight. Overall, the OnePlus Watch 3 scores 53.9 and the Watch S4 scores 63.9 on our Mars Score.
Which should you buy?
The Watch S4 is the clear pick on raw spec strength, leading by 10.0 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 OnePlus Watch 3 if you care most about display size. The biggest gaps in its favor are display size.
Pick the Watch S4 if your top frustration with your current device is running out of charge before the day ends — endurance is the lead spec here. Its strongest claims are battery life, weight, cellular.
Both ship with comparable ecg, spo2, water resistance, so those specs don't separate the two — focus on the differences below.
Bottom line: the Watch S4 is the safer default. The other model is the right choice only when its specific advantages line up with your priorities.
Why OnePlus Watch 3 wins
- ▲Display size — 4.90% more. 1.5 " vs 1.43 ".
Why Xiaomi - Watch S4 wins
- ▲Battery life — 200.00% more. 360 h vs 120 h.
- ▲Weight — 37.00 g less. 44 vs 81.
- ▲Has Cellular.
Spec comparison
Design
| Spec | OnePlus Watch 3 | Xiaomi - Watch S4 |
|---|---|---|
| Case size | 46.5 mm | 47 mmlead |
| Weight | 81 g | 44 glead |
| Case material | stainless steel | stainless steel |
| Water resistanceⓘ | 5 ATM | 5 ATM |
Display
| Spec | OnePlus Watch 3 | Xiaomi - Watch S4 |
|---|---|---|
| Display size | 1.5 "lead | 1.43 " |
| Always-on display | true | true |
| Peak brightnessⓘ | 2200 nits | 2200 nits |
Health & Fitness
| Spec | OnePlus Watch 3 | Xiaomi - Watch S4 |
|---|---|---|
| ECG | true | true |
| SpO2 | true | true |
| Temperature sensor | true | true |
| Sleep tracking | true | true |
| Blood pressure | false | false |
Battery & Connectivity
| Spec | OnePlus Watch 3 | Xiaomi - Watch S4 |
|---|---|---|
| Battery life | 120 h | 360 hlead |
| GPS | true | true |
| Cellular | false | truelead |
| NFC | true | true |
| OS | WearOS | HyperOSlead |
Frequently asked
Which has longer battery life, OnePlus Watch 3 or Watch S4?+
Watch S4 lasts 360h vs 120h.
Do OnePlus Watch 3 or Watch S4 support ECG?+
Both support ECG.
Which has cellular, OnePlus Watch 3 or Watch S4?+
Watch S4 offers a cellular variant; OnePlus Watch 3 is Wi-Fi only.
Spec-level deep dives
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