Where they actually differ
The most decisive specs, ranked by how much they matter — before the full spec table.
| Spec | Garmin - Fenix 8 Solar (47mm) | Polar - Grit X2 Pro |
|---|---|---|
| Smartwatch mode | 28 days | 10 days |
| GPS mode | 104 h | 43 h |
| Solar charging | true | false |
Between the Fenix 8 Solar (47mm) and Grit X2 Pro, the Fenix 8 Solar (47mm) comes out ahead in smartwatch mode / gps mode, while the Grit X2 Pro wins on several specs. Overall, the Fenix 8 Solar (47mm) scores 73.5 and the Grit X2 Pro scores 68.3 on our Mars Score.
Which should you buy?
The Fenix 8 Solar (47mm) edges ahead on the Mars Score (73.5 vs 68.3), but the 5.2-point gap is small enough that the right pick comes down to which spec advantages matter to you.
Pick the Fenix 8 Solar (47mm) if you care most about smartwatch mode / gps mode. The biggest gaps in its favor are smartwatch mode, gps mode, solar charging. The single most decisive one: Smartwatch mode — 180.00% more. 28 days vs 10 days.
The Grit X2 Pro similarly does not carry a headline advantage on the popular specs — look at the full table for category-specific deltas.
Both ship with comparable multi-band gps, ecg, so those specs do not separate the two — focus on the differences below.
Bottom line: the Fenix 8 Solar (47mm) 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 - Fenix 8 Solar (47mm) or Polar - Grit X2 Pro?
Garmin - Fenix 8 Solar (47mm) leads the current Mars Score by 5.2 points.The more useful decision is the trade-off behind that result: compare smartwatch mode, gps mode against the way you will actually use the product.
Choose Garmin - Fenix 8 Solar (47mm) if…
Garmin - Fenix 8 Solar (47mm) has the measurable edge on battery smartwatch days, battery gps hours, has solar.
Choose Polar - Grit X2 Pro if…
Polar - Grit X2 Pro does not lead a decisive measured field here, so choose it for price, ecosystem, design, or availability when those matter more to you.
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 - Fenix 8 Solar (47mm) wins
- ▲Smartwatch mode — 180.00% more. 28 days vs 10 days.
- ▲GPS mode — 141.86% more. 104 h vs 43 h.
- ▲Has Solar charging.
Why Polar - Grit X2 Pro wins
- No decisive advantages.
Spec comparison
GPS & Sensors
| Spec | Garmin - Fenix 8 Solar (47mm) | Polar - Grit X2 Pro |
|---|---|---|
| Multi-band GPS | true | true |
| Barometric altimeter | true | true |
| Heart rate | true | true |
| ECG | true | true |
| Pulse Ox | true | true |
Battery
| Spec | Garmin - Fenix 8 Solar (47mm) | Polar - Grit X2 Pro |
|---|---|---|
| Smartwatch mode | 28 dayslead | 10 days |
| GPS mode | 104 hlead | 43 h |
| Solar charging | truelead | false |
Design
| Spec | Garmin - Fenix 8 Solar (47mm) | Polar - Grit X2 Pro |
|---|---|---|
| Case size | 47 mm | 47.5 mmlead |
| Weight | 82 g | 79 glead |
| Water resistanceⓘ | 10 ATM | 10 ATM |