Where they actually differ
The most decisive specs, ranked by how much they matter — before the full spec table.
| Spec | OnePlus Watch 3 | Google - Pixel Watch 3 (45mm) |
|---|---|---|
| Battery life | 120 h | 36 h |
| Weight | 81 g | 37 g |
| Peak brightness | 2200 nits | 2000 nits |
| Display size | 1.5 " | 1.4 " |
| Cellular | false | true |
Between the OnePlus Watch 3 and Pixel Watch 3 (45mm), the OnePlus Watch 3 comes out ahead in battery life / peak brightness, while the Pixel Watch 3 (45mm) wins on weight / cellular. Overall, the OnePlus Watch 3 scores 65.7 and the Pixel Watch 3 (45mm) scores 69.5 on our Mars Score.
Which should you buy?
The Pixel Watch 3 (45mm) edges ahead on the Mars Score (65.7 vs 69.5), but the 3.8-point gap is small enough that the right pick comes down to which spec advantages matter to you.
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. The biggest gaps in its favor are battery life, peak brightness, display size. The single most decisive one: Battery life — 233.33% more. 120 h vs 36 h.
Pick the Pixel Watch 3 (45mm) if you carry the device everywhere and weight or thickness has been the deciding factor before. Its strongest claims are weight, cellular. The single most decisive one: Weight — 44.00 g less. 37 vs 81.
Both ship with comparable ecg, spo2, 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.
Which should you buy: OnePlus Watch 3 or Google - Pixel Watch 3 (45mm)?
Google - Pixel Watch 3 (45mm) leads the current Mars Score by 3.8 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 battery life h, peak brightness nits, display size in.
Choose Google - Pixel Watch 3 (45mm) if…
Google - Pixel Watch 3 (45mm) has the measurable edge on weight g, has cellular.
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
- ▲Battery life — 233.33% more. 120 h vs 36 h.
- ▲Peak brightness — 10.00% more. 2200 nits vs 2000 nits.
- ▲Display size — 7.14% more. 1.5 " vs 1.4 ".
Why Google - Pixel Watch 3 (45mm) wins
- ▲Weight — 44.00 g less. 37 vs 81.
- ▲Has Cellular.
Spec comparison
Design
| Spec | OnePlus Watch 3 | Google - Pixel Watch 3 (45mm) |
|---|---|---|
| Case size | 46.5 mmlead | 45 mm |
| Weight | 81 g | 37 glead |
| Case material | stainless steel | aluminum |
| Water resistanceⓘ | 5 ATM | 5 ATM |
Display
| Spec | OnePlus Watch 3 | Google - Pixel Watch 3 (45mm) |
|---|---|---|
| Display size | 1.5 "lead | 1.4 " |
| Always-on display | true | true |
| Peak brightnessⓘ | 2200 nitslead | 2000 nits |
Health & Fitness
| Spec | OnePlus Watch 3 | Google - Pixel Watch 3 (45mm) |
|---|---|---|
| ECG | true | true |
| SpO2 | true | true |
| Temperature sensor | true | true |
| Sleep tracking | true | true |
| Blood pressure | false | false |
Battery & Connectivity
| Spec | OnePlus Watch 3 | Google - Pixel Watch 3 (45mm) |
|---|---|---|
| Battery lifeⓘ | 120 hlead | 36 h |
| GPS | true | true |
| Cellular | false | truelead |
| NFC | true | true |
| OS | WearOS | WearOS |
Frequently asked
Which has longer battery life, OnePlus Watch 3 or Pixel Watch 3 (45mm)?+
OnePlus Watch 3 lasts 120 hours vs 36 hours.
Do OnePlus Watch 3 or Pixel Watch 3 (45mm) support ECG?+
Both support ECG.
Which has cellular, OnePlus Watch 3 or Pixel Watch 3 (45mm)?+
Pixel Watch 3 (45mm) offers a cellular variant; OnePlus Watch 3 is Wi-Fi only.