Where they actually differ
The most decisive specs, ranked by how much they matter — before the full spec table.
| Spec | OnePlus Watch 3 | Withings - ScanWatch 2 |
|---|---|---|
| Battery life | 120 h | 720 h |
| Display size | 1.5 " | 0.63 " |
| Weight | 81 g | 59 g |
| Peak brightness | 2200 nits | 0 nits |
Between the OnePlus Watch 3 and ScanWatch 2, the OnePlus Watch 3 comes out ahead in display size / peak brightness, while the ScanWatch 2 wins on battery life / weight. Overall, the OnePlus Watch 3 scores 65.7 and the ScanWatch 2 scores 78.3 on our Mars Score.
Which should you buy?
The ScanWatch 2 is the clear pick on raw spec strength, leading by 12.6 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 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 display size, peak brightness. The single most decisive one: Display size — 138.10% more. 1.5 " vs 0.63 ".
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. Its strongest claims are battery life, weight. The single most decisive one: Battery life — 500.00% more. 720 h vs 120 h.
Both ship with comparable ecg, cellular, spo2, so those specs do not 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.
Which should you buy: OnePlus Watch 3 or Withings - ScanWatch 2?
Withings - ScanWatch 2 leads the current Mars Score by 12.6 points.The more useful decision is the trade-off behind that result: compare display size, battery life against the way you will actually use the product.
Choose OnePlus Watch 3 if…
OnePlus Watch 3 has the measurable edge on display size in, peak brightness nits.
Choose Withings - ScanWatch 2 if…
Withings - ScanWatch 2 has the measurable edge on battery life h, weight g.
This is a structured comparison of the published catalog values. It is not a claim of identical real-world performance across every workload; use the linked spec drill-downs and methodology page to inspect the inputs.
Why OnePlus Watch 3 wins
- ▲Display size — 138.10% more. 1.5 " vs 0.63 ".
- ▲Peak brightness: 2200 nits vs 0 nits.
Why Withings - ScanWatch 2 wins
- ▲Battery life — 500.00% more. 720 h vs 120 h.
- ▲Weight — 22.00 g less. 59 vs 81.
Spec comparison
Design
| Spec | OnePlus Watch 3 | Withings - ScanWatch 2 |
|---|---|---|
| Case size | 46.5 mmlead | 42 mm |
| Weight | 81 g | 59 glead |
| Case material | stainless steel | stainless steel |
| Water resistanceⓘ | 5 ATM | 5 ATM |
Display
| Spec | OnePlus Watch 3 | Withings - ScanWatch 2 |
|---|---|---|
| Display size | 1.5 "lead | 0.63 " |
| Always-on display | truelead | false |
| Peak brightnessⓘ | 2200 nitslead | 0 nits |
Health & Fitness
| Spec | OnePlus Watch 3 | Withings - ScanWatch 2 |
|---|---|---|
| ECG | true | true |
| SpO2 | true | true |
| Temperature sensor | true | true |
| Sleep tracking | true | true |
| Blood pressure | false | false |
Battery & Connectivity
| Spec | OnePlus Watch 3 | Withings - ScanWatch 2 |
|---|---|---|
| Battery lifeⓘ | 120 h | 720 hlead |
| GPS | truelead | false |
| Cellular | false | false |
| NFC | truelead | false |
| OS | WearOS | Withings OSlead |
Frequently asked
Which has longer battery life, OnePlus Watch 3 or ScanWatch 2?+
ScanWatch 2 lasts 720 hours vs 120 hours.
Do OnePlus Watch 3 or ScanWatch 2 support ECG?+
Both support ECG.
Which has cellular, OnePlus Watch 3 or ScanWatch 2?+
Neither offers cellular.