Between the T-Rex 3 and vívoactive 5, the T-Rex 3 comes out ahead in battery life and peak brightness, while the vívoactive 5 wins on weight. Overall, the T-Rex 3 scores 79.7 and the vívoactive 5 scores 53.3 on our Mars Score.
Which should you buy?
The T-Rex 3 is the clear pick on raw spec strength, leading by 26.4 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 T-Rex 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, among others.
Pick the vívoactive 5 if you carry the device everywhere and weight or thickness has been the deciding factor before. Its strongest claims are weight.
Both ship with comparable ecg, cellular, spo2, so those specs don't separate the two — focus on the differences below.
Bottom line: the T-Rex 3 is the safer default. The other model is the right choice only when its specific advantages line up with your priorities.
Why Amazfit - T-Rex 3 wins
- ▲Battery life — 154.55% more. 672 h vs 264 h.
- ▲Peak brightness — 100.00% more. 2000 nits vs 1000 nits.
- ▲Display size — 25.00% more. 1.5 " vs 1.2 ".
- ▲Water resistance — 5.00 ATM more. 10 vs 5.
Why Garmin - vívoactive 5 wins
- ▲Weight — 42.00 g less. 26 vs 68.
Spec comparison
Design
| Spec | Amazfit - T-Rex 3 | Garmin - vívoactive 5 |
|---|---|---|
| Case size | 48.5 mmlead | 42 mm |
| Weight | 68 g | 26 glead |
| Case material | polymer | polymer |
| Water resistanceⓘ | 10 ATMlead | 5 ATM |
Display
| Spec | Amazfit - T-Rex 3 | Garmin - vívoactive 5 |
|---|---|---|
| Display size | 1.5 "lead | 1.2 " |
| Always-on display | true | true |
| Peak brightnessⓘ | 2000 nitslead | 1000 nits |
Health & Fitness
| Spec | Amazfit - T-Rex 3 | Garmin - vívoactive 5 |
|---|---|---|
| ECG | false | false |
| SpO2 | true | true |
| Temperature sensor | truelead | false |
| Sleep tracking | true | true |
| Blood pressure | false | false |
Battery & Connectivity
| Spec | Amazfit - T-Rex 3 | Garmin - vívoactive 5 |
|---|---|---|
| Battery life | 672 hlead | 264 h |
| GPS | true | true |
| Cellular | false | false |
| NFC | false | truelead |
| OS | Zepp OSlead | Garmin OS |
Frequently asked
Which has longer battery life, T-Rex 3 or vívoactive 5?+
T-Rex 3 lasts 672h vs 264h.
Do T-Rex 3 or vívoactive 5 support ECG?+
Neither supports ECG.
Which has cellular, T-Rex 3 or vívoactive 5?+
Neither offers cellular.
Spec-level deep dives
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