Where they actually differ
The most decisive specs, ranked by how much they matter — before the full spec table.
| Spec | Amazfit - T-Rex 3 | Apple - Watch SE 3 |
|---|---|---|
| Battery life | 672 h | 18 h |
| Peak brightness | 2000 nits | 1000 nits |
| Weight | 68 g | 33 g |
| Display size | 1.5 " | 1.78 " |
| Water resistance | 10 ATM | 5 ATM |
| SpO2 | true | false |
Between the T-Rex 3 and Watch SE 3, the T-Rex 3 comes out ahead in battery life / peak brightness, while the Watch SE 3 wins on weight / display size. Overall, the T-Rex 3 scores 62.7 and the Watch SE 3 scores 55.9 on our Mars Score.
Which should you buy?
The T-Rex 3 edges ahead on the Mars Score (62.7 vs 55.9), but the 6.8-point gap is small enough that the right pick comes down to which spec advantages matter to you.
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, water resistance, among others. The single most decisive one: Battery life — 3633.33% more. 672 h vs 18 h.
Pick the Watch SE 3 if you carry the device everywhere and weight or thickness has been the deciding factor before. Its strongest claims are weight, display size, cellular. The single most decisive one: Weight — 35.00 g less. 33 vs 68.
Both ship with comparable ecg, so those specs do not 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.
Which should you buy: Amazfit - T-Rex 3 or Apple - Watch SE 3?
Amazfit - T-Rex 3 leads the current Mars Score by 6.8 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 Amazfit - T-Rex 3 if…
Amazfit - T-Rex 3 has the measurable edge on battery life h, peak brightness nits, water resistance atm.
Choose Apple - Watch SE 3 if…
Apple - Watch SE 3 has the measurable edge on weight g, display size in, 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 Amazfit - T-Rex 3 wins
- ▲Battery life — 3633.33% more. 672 h vs 18 h.
- ▲Peak brightness — 100.00% more. 2000 nits vs 1000 nits.
- ▲Water resistance — 5.00 ATM more. 10 vs 5.
- ▲Has SpO2.
Why Apple - Watch SE 3 wins
- ▲Weight — 35.00 g less. 33 vs 68.
- ▲Display size — 18.67% more. 1.78 " vs 1.5 ".
- ▲Has Cellular.
Spec comparison
Design
| Spec | Amazfit - T-Rex 3 | Apple - Watch SE 3 |
|---|---|---|
| Case size | 48.5 mmlead | 44 mm |
| Weight | 68 g | 33 glead |
| Case material | polymer | aluminum |
| Water resistanceⓘ | 10 ATMlead | 5 ATM |
Display
| Spec | Amazfit - T-Rex 3 | Apple - Watch SE 3 |
|---|---|---|
| Display size | 1.5 " | 1.78 "lead |
| Always-on display | true | true |
| Peak brightnessⓘ | 2000 nitslead | 1000 nits |
Health & Fitness
| Spec | Amazfit - T-Rex 3 | Apple - Watch SE 3 |
|---|---|---|
| ECG | false | false |
| SpO2 | truelead | false |
| Temperature sensor | true | true |
| Sleep tracking | true | true |
| Blood pressure | false | false |
Battery & Connectivity
| Spec | Amazfit - T-Rex 3 | Apple - Watch SE 3 |
|---|---|---|
| Battery lifeⓘ | 672 hlead | 18 h |
| GPS | true | true |
| Cellular | false | truelead |
| NFC | false | truelead |
| OS | Zepp OSlead | watchOS |
Frequently asked
Which has longer battery life, T-Rex 3 or Watch SE 3?+
T-Rex 3 lasts 672 hours vs 18 hours.
Do T-Rex 3 or Watch SE 3 support ECG?+
Neither supports ECG.
Which has cellular, T-Rex 3 or Watch SE 3?+
Watch SE 3 offers a cellular variant; T-Rex 3 is Wi-Fi only.