Between the Galaxy Watch 7 (40mm) and OnePlus Watch 3, the Galaxy Watch 7 (40mm) comes out ahead in weight and peak brightness, while the OnePlus Watch 3 wins on battery life and display size. Overall, the Galaxy Watch 7 (40mm) scores 43.8 and the OnePlus Watch 3 scores 53.9 on our Mars Score.
Which should you buy?
The OnePlus Watch 3 is the clear pick on raw spec strength, leading by 10.1 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 Galaxy Watch 7 (40mm) if the display is what you stare at all day — refresh rate, brightness, or sharpness is where the difference will be most visible. The biggest gaps in its favor are weight, peak brightness, 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, display size.
Both ship with comparable ecg, spo2, water resistance, so those specs don't separate the two — focus on the differences below.
Bottom line: the OnePlus Watch 3 is the safer default. The other model is the right choice only when its specific advantages line up with your priorities.
Why Samsung - Galaxy Watch 7 (40mm) wins
- ▲Weight — 52.20 g less. 28.8 vs 81.
- ▲Peak brightness — 36.36% more. 3000 nits vs 2200 nits.
- ▲Has Cellular.
Why OnePlus Watch 3 wins
- ▲Battery life — 300.00% more. 120 h vs 30 h.
- ▲Display size — 14.50% more. 1.5 " vs 1.31 ".
Spec comparison
Design
| Spec | Samsung - Galaxy Watch 7 (40mm) | OnePlus Watch 3 |
|---|---|---|
| Case size | 40 mm | 46.5 mmlead |
| Weight | 28.8 glead | 81 g |
| Case material | aluminum | stainless steel |
| Water resistanceⓘ | 5 ATM | 5 ATM |
Display
| Spec | Samsung - Galaxy Watch 7 (40mm) | OnePlus Watch 3 |
|---|---|---|
| Display size | 1.31 " | 1.5 "lead |
| Always-on display | true | true |
| Peak brightnessⓘ | 3000 nitslead | 2200 nits |
Health & Fitness
| Spec | Samsung - Galaxy Watch 7 (40mm) | OnePlus Watch 3 |
|---|---|---|
| ECG | true | true |
| SpO2 | true | true |
| Temperature sensor | true | true |
| Sleep tracking | true | true |
| Blood pressure | truelead | false |
Battery & Connectivity
| Spec | Samsung - Galaxy Watch 7 (40mm) | OnePlus Watch 3 |
|---|---|---|
| Battery life | 30 h | 120 hlead |
| GPS | true | true |
| Cellular | truelead | false |
| NFC | true | true |
| OS | WearOS | WearOS |
Frequently asked
Which has longer battery life, Galaxy Watch 7 (40mm) or OnePlus Watch 3?+
OnePlus Watch 3 lasts 120h vs 30h.
Do Galaxy Watch 7 (40mm) or OnePlus Watch 3 support ECG?+
Both support ECG.
Which has cellular, Galaxy Watch 7 (40mm) or OnePlus Watch 3?+
Galaxy Watch 7 (40mm) offers a cellular variant; OnePlus Watch 3 is Wi-Fi only.
Spec-level deep dives
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