Between the Watch SE 3 and Fenix 8 (47mm), the Watch SE 3 comes out ahead in weight and display size, while the Fenix 8 (47mm) wins on battery life and water resistance. Overall, the Watch SE 3 scores 56.1 and the Fenix 8 (47mm) scores 64.3 on our Mars Score.
Which should you buy?
The Fenix 8 (47mm) is the clear pick on raw spec strength, leading by 8.2 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 Watch SE 3 if you carry the device everywhere and weight or thickness has been the deciding factor before. The biggest gaps in its favor are weight, display size, cellular.
Pick the Fenix 8 (47mm) 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, water resistance, ecg, among others.
Both ship with comparable peak brightness, so those specs don't separate the two — focus on the differences below.
Bottom line: the Fenix 8 (47mm) is the safer default. The other model is the right choice only when its specific advantages line up with your priorities.
Why Apple - Watch SE 3 wins
- ▲Weight — 40.00 g less. 33 vs 73.
- ▲Display size — 27.14% more. 1.78 " vs 1.4 ".
- ▲Has Cellular.
Why Garmin - Fenix 8 (47mm) wins
- ▲Battery life — 2033.33% more. 384 h vs 18 h.
- ▲Water resistance — 5.00 ATM more. 10 vs 5.
- ▲Has ECG.
- ▲Has SpO2.
Spec comparison
Design
| Spec | Apple - Watch SE 3 | Garmin - Fenix 8 (47mm) |
|---|---|---|
| Case size | 44 mm | 47 mmlead |
| Weight | 33 glead | 73 g |
| Case material | aluminum | fiber-reinforced polymer |
| Water resistanceⓘ | 5 ATM | 10 ATMlead |
Display
| Spec | Apple - Watch SE 3 | Garmin - Fenix 8 (47mm) |
|---|---|---|
| Display size | 1.78 "lead | 1.4 " |
| Always-on display | false | truelead |
| Peak brightnessⓘ | 1000 nits | 1000 nits |
Health & Fitness
| Spec | Apple - Watch SE 3 | Garmin - Fenix 8 (47mm) |
|---|---|---|
| ECG | false | truelead |
| SpO2 | false | truelead |
| Temperature sensor | false | truelead |
| Sleep tracking | true | true |
| Blood pressure | false | false |
Battery & Connectivity
| Spec | Apple - Watch SE 3 | Garmin - Fenix 8 (47mm) |
|---|---|---|
| Battery life | 18 h | 384 hlead |
| GPS | true | true |
| Cellular | truelead | false |
| NFC | true | true |
| OS | watchOS | Garmin OSlead |
Frequently asked
Which has longer battery life, Watch SE 3 or Fenix 8 (47mm)?+
Fenix 8 (47mm) lasts 384h vs 18h.
Do Watch SE 3 or Fenix 8 (47mm) support ECG?+
Fenix 8 (47mm) supports ECG; Watch SE 3 does not.
Which has cellular, Watch SE 3 or Fenix 8 (47mm)?+
Watch SE 3 offers a cellular variant; Fenix 8 (47mm) is Wi-Fi only.
Spec-level deep dives
More from the same brands
vsMars is reader-supported. When you buy through links on our site, we may earn an affiliate commission at no extra cost to you. Learn more.