Where they actually differ
The most decisive specs, ranked by how much they matter — before the full spec table.
| Spec | Garmin - vívoactive 5 | OnePlus Watch 3 |
|---|---|---|
| Battery life | 264 h | 120 h |
| Peak brightness | 1000 nits | 2200 nits |
| Weight | 26 g | 81 g |
| Display size | 1.2 " | 1.5 " |
| ECG | false | true |
Between the vívoactive 5 and OnePlus Watch 3, the vívoactive 5 comes out ahead in battery life / weight, while the OnePlus Watch 3 wins on peak brightness / display size. Overall, the vívoactive 5 scores 55.7 and the OnePlus Watch 3 scores 65.7 on our Mars Score.
Which should you buy?
The OnePlus Watch 3 is the clear pick on raw spec strength, leading by 10.0 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 vívoactive 5 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, weight. The single most decisive one: Battery life — 120.00% more. 264 h vs 120 h.
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. Its strongest claims are peak brightness, display size, ecg. The single most decisive one: Peak brightness — 120.00% more. 2200 nits vs 1000 nits.
Both ship with comparable cellular, spo2, water resistance, so those specs do not 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.
Which should you buy: Garmin - vívoactive 5 or OnePlus Watch 3?
OnePlus Watch 3 leads the current Mars Score by 10.0 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 Garmin - vívoactive 5 if…
Garmin - vívoactive 5 has the measurable edge on battery life h, weight g.
Choose OnePlus Watch 3 if…
OnePlus Watch 3 has the measurable edge on peak brightness nits, display size in, has ecg.
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 Garmin - vívoactive 5 wins
- ▲Battery life — 120.00% more. 264 h vs 120 h.
- ▲Weight — 55.00 g less. 26 vs 81.
Why OnePlus Watch 3 wins
- ▲Peak brightness — 120.00% more. 2200 nits vs 1000 nits.
- ▲Display size — 25.00% more. 1.5 " vs 1.2 ".
- ▲Has ECG.
Spec comparison
Design
| Spec | Garmin - vívoactive 5 | OnePlus Watch 3 |
|---|---|---|
| Case size | 42 mm | 46.5 mmlead |
| Weight | 26 glead | 81 g |
| Case material | polymer | stainless steel |
| Water resistanceⓘ | 5 ATM | 5 ATM |
Display
| Spec | Garmin - vívoactive 5 | OnePlus Watch 3 |
|---|---|---|
| Display size | 1.2 " | 1.5 "lead |
| Always-on display | true | true |
| Peak brightnessⓘ | 1000 nits | 2200 nitslead |
Health & Fitness
| Spec | Garmin - vívoactive 5 | OnePlus Watch 3 |
|---|---|---|
| ECG | false | truelead |
| SpO2 | true | true |
| Temperature sensor | false | truelead |
| Sleep tracking | true | true |
| Blood pressure | false | false |
Battery & Connectivity
| Spec | Garmin - vívoactive 5 | OnePlus Watch 3 |
|---|---|---|
| Battery lifeⓘ | 264 hlead | 120 h |
| GPS | true | true |
| Cellular | false | false |
| NFC | true | true |
| OS | Garmin OSlead | WearOS |
Frequently asked
Which has longer battery life, vívoactive 5 or OnePlus Watch 3?+
vívoactive 5 lasts 264 hours vs 120 hours.
Do vívoactive 5 or OnePlus Watch 3 support ECG?+
OnePlus Watch 3 supports ECG; vívoactive 5 does not.
Which has cellular, vívoactive 5 or OnePlus Watch 3?+
Neither offers cellular.