Where they actually differ
The most decisive specs, ranked by how much they matter — before the full spec table.
| Spec | Apple - Watch Ultra 2 | OnePlus Watch 3 |
|---|---|---|
| Battery life | 36 h | 120 h |
| Peak brightness | 3000 nits | 2200 nits |
| Display size | 1.92 " | 1.5 " |
| Weight | 61.4 g | 81 g |
| Water resistance | 10 ATM | 5 ATM |
| Cellular | true | false |
Between the Watch Ultra 2 and OnePlus Watch 3, the Watch Ultra 2 comes out ahead in peak brightness / display size, while the OnePlus Watch 3 wins on battery life. Overall, the Watch Ultra 2 scores 71.9 and the OnePlus Watch 3 scores 65.7 on our Mars Score.
Which should you buy?
The Watch Ultra 2 edges ahead on the Mars Score (71.9 vs 65.7), but the 6.2-point gap is small enough that the right pick comes down to which spec advantages matter to you.
Pick the Watch Ultra 2 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 peak brightness, display size, weight, among others. The single most decisive one: Peak brightness — 36.36% more. 3000 nits vs 2200 nits.
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. The single most decisive one: Battery life — 233.33% more. 120 h vs 36 h.
Both ship with comparable ecg, spo2, so those specs do not separate the two — focus on the differences below.
Bottom line: the Watch Ultra 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: Apple - Watch Ultra 2 or OnePlus Watch 3?
Apple - Watch Ultra 2 leads the current Mars Score by 6.2 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 Apple - Watch Ultra 2 if…
Apple - Watch Ultra 2 has the measurable edge on peak brightness nits, display size in, weight g.
Choose OnePlus Watch 3 if…
OnePlus Watch 3 has the measurable edge on battery life h.
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 Apple - Watch Ultra 2 wins
- ▲Peak brightness — 36.36% more. 3000 nits vs 2200 nits.
- ▲Display size — 28.00% more. 1.92 " vs 1.5 ".
- ▲Weight — 19.60 g less. 61.4 vs 81.
- ▲Water resistance — 5.00 ATM more. 10 vs 5.
- ▲Has Cellular.
Why OnePlus Watch 3 wins
- ▲Battery life — 233.33% more. 120 h vs 36 h.
Spec comparison
Design
| Spec | Apple - Watch Ultra 2 | OnePlus Watch 3 |
|---|---|---|
| Case size | 49 mmlead | 46.5 mm |
| Weight | 61.4 glead | 81 g |
| Case material | titanium | stainless steel |
| Water resistanceⓘ | 10 ATMlead | 5 ATM |
Display
| Spec | Apple - Watch Ultra 2 | OnePlus Watch 3 |
|---|---|---|
| Display size | 1.92 "lead | 1.5 " |
| Always-on display | true | true |
| Peak brightnessⓘ | 3000 nitslead | 2200 nits |
Health & Fitness
| Spec | Apple - Watch Ultra 2 | OnePlus Watch 3 |
|---|---|---|
| ECG | true | true |
| SpO2 | true | true |
| Temperature sensor | true | true |
| Sleep tracking | true | true |
| Blood pressure | false | false |
Battery & Connectivity
| Spec | Apple - Watch Ultra 2 | OnePlus Watch 3 |
|---|---|---|
| Battery lifeⓘ | 36 h | 120 hlead |
| GPS | true | true |
| Cellular | truelead | false |
| NFC | true | true |
| OS | watchOS | WearOSlead |
Frequently asked
Which has longer battery life, Watch Ultra 2 or OnePlus Watch 3?+
OnePlus Watch 3 lasts 120 hours vs 36 hours.
Do Watch Ultra 2 or OnePlus Watch 3 support ECG?+
Both support ECG.
Which has cellular, Watch Ultra 2 or OnePlus Watch 3?+
Watch Ultra 2 offers a cellular variant; OnePlus Watch 3 is Wi-Fi only.