Where they actually differ
The most decisive specs, ranked by how much they matter — before the full spec table.
| Spec | Google - Fitbit Charge 6 | Oura - Ring 4 |
|---|---|---|
| Battery life | 7 days | 8 days |
| Water resistance | 5 ATM | 10 ATM |
| GPS | true | false |
Between the Fitbit Charge 6 and Ring 4, the Fitbit Charge 6 comes out ahead in gps, while the Ring 4 wins on battery life / water resistance. Overall, the Fitbit Charge 6 scores 77.4 and the Ring 4 scores 63.8 on our Mars Score.
Which should you buy?
The Fitbit Charge 6 is the clear pick on raw spec strength, leading by 13.6 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 Fitbit Charge 6 if you care most about gps. The biggest gaps in its favor are gps. The single most decisive one: Has GPS.
Pick the Ring 4 if you care most about battery life / water resistance. Its strongest claims are battery life, water resistance. The single most decisive one: Battery life — 14.29% more. 8 days vs 7 days.
Both ship with comparable sport modes, spo2, so those specs do not separate the two — focus on the differences below.
Bottom line: the Fitbit Charge 6 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: Google - Fitbit Charge 6 or Oura - Ring 4?
Google - Fitbit Charge 6 leads the current Mars Score by 13.6 points.The more useful decision is the trade-off behind that result: compare battery life, gps against the way you will actually use the product.
Choose Google - Fitbit Charge 6 if…
Google - Fitbit Charge 6 has the measurable edge on has gps.
Choose Oura - Ring 4 if…
Oura - Ring 4 has the measurable edge on battery days, water resistance atm.
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 Google - Fitbit Charge 6 wins
- ▲Has GPS.
Why Oura - Ring 4 wins
- ▲Battery life — 14.29% more. 8 days vs 7 days.
- ▲Water resistance — 5.00 ATM more. 10 vs 5.
Spec comparison
Fitness
| Spec | Google - Fitbit Charge 6 | Oura - Ring 4 |
|---|---|---|
| Form factor | Band | Ringlead |
| GPS | truelead | false |
| Heart rate | true | true |
| SpO2 | true | true |
| Sleep tracking | true | true |
| Sport modes | 40 | 40 |
Battery
| Spec | Google - Fitbit Charge 6 | Oura - Ring 4 |
|---|---|---|
| Battery lifeⓘ | 7 days | 8 dayslead |
| Water resistanceⓘ | 5 ATM | 10 ATMlead |
Design
| Spec | Google - Fitbit Charge 6 | Oura - Ring 4 |
|---|---|---|
| Display size | 1.04 "lead | 0 " |
| Weight | 37 g | 3.3 glead |