Between the Watch SE 3 and OnePlus Watch 3, the Watch SE 3 comes out ahead in weight / display size, while the OnePlus Watch 3 wins on battery life / peak brightness. Overall, the Watch SE 3 scores 56.1 and the OnePlus Watch 3 scores 53.9 on our Mars Score.
Which should you buy?
These two are nearly even on the Mars Score (56.1 vs 53.9). The decision is not about overall quality — both clear the bar — it is about which specific trade-offs fit your use.
Pick the Watch SE 3 if you carry the device everywhere and weight or thickness has been the deciding factor before. The biggest gaps in its favor are weight, display size, cellular.
Pick the OnePlus Watch 3 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, peak brightness, ecg, among others.
Both ship with comparable water resistance, so those specs do not separate the two — focus on the differences below.
Bottom line: there is no wrong answer here — match the spec advantages to how you actually use the product. The Mars Score parity says both are well-rounded; the differences are about trade-offs, not quality.
Why Apple - Watch SE 3 wins
- ▲Weight — 48.00 g less. 33 vs 81.
- ▲Display size — 18.67% more. 1.78 " vs 1.5 ".
- ▲Has Cellular.
Why OnePlus Watch 3 wins
- ▲Battery life — 566.67% more. 120 h vs 18 h.
- ▲Peak brightness — 120.00% more. 2200 nits vs 1000 nits.
- ▲Has ECG.
- ▲Has SpO2.
Spec comparison
Design
| Spec | Apple - Watch SE 3 | OnePlus Watch 3 |
|---|---|---|
| Case size | 44 mm | 46.5 mmlead |
| Weight | 33 glead | 81 g |
| Case material | aluminum | stainless steel |
| Water resistanceⓘ | 5 ATM | 5 ATM |
Display
| Spec | Apple - Watch SE 3 | OnePlus Watch 3 |
|---|---|---|
| Display size | 1.78 "lead | 1.5 " |
| Always-on display | false | truelead |
| Peak brightnessⓘ | 1000 nits | 2200 nitslead |
Health & Fitness
| Spec | Apple - Watch SE 3 | OnePlus Watch 3 |
|---|---|---|
| ECG | false | truelead |
| SpO2 | false | truelead |
| Temperature sensor | false | truelead |
| Sleep tracking | true | true |
| Blood pressure | false | false |
Battery & Connectivity
| Spec | Apple - Watch SE 3 | OnePlus Watch 3 |
|---|---|---|
| Battery life | 18 h | 120 hlead |
| GPS | true | true |
| Cellular | truelead | false |
| NFC | true | true |
| OS | watchOS | WearOSlead |
Frequently asked
Which has longer battery life, Watch SE 3 or OnePlus Watch 3?+
OnePlus Watch 3 lasts 120 hours vs 18 hours.
Do Watch SE 3 or OnePlus Watch 3 support ECG?+
OnePlus Watch 3 supports ECG; Watch SE 3 does not.
Which has cellular, Watch SE 3 or OnePlus Watch 3?+
Watch SE 3 offers a cellular variant; OnePlus Watch 3 is Wi-Fi only.
Spec-level deep dives
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