Where they actually differ
The most decisive specs, ranked by how much they matter — before the full spec table.
| Spec | Huawei - Watch Ultimate | Xiaomi - Watch S4 |
|---|---|---|
| Peak brightness | 1000 nits | 2200 nits |
| Weight | 76 g | 44 g |
| Battery life | 336 h | 360 h |
| Water resistance | 10 ATM | 5 ATM |
| Display size | 1.5 " | 1.43 " |
| Cellular | false | true |
Between the Watch Ultimate and Watch S4, the Watch Ultimate comes out ahead in water resistance / display size, while the Watch S4 wins on peak brightness / weight. Overall, the Watch Ultimate scores 71.5 and the Watch S4 scores 76.3 on our Mars Score.
Which should you buy?
The Watch S4 edges ahead on the Mars Score (71.5 vs 76.3), but the 4.8-point gap is small enough that the right pick comes down to which spec advantages matter to you.
Pick the Watch Ultimate if you care most about water resistance / display size. The biggest gaps in its favor are water resistance, display size. The single most decisive one: Water resistance — 5.00 ATM more. 10 vs 5.
Pick the Watch S4 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 peak brightness, weight, battery life, among others. The single most decisive one: Peak brightness — 120.00% more. 2200 nits vs 1000 nits.
Both ship with comparable ecg, spo2, so those specs do not separate the two — focus on the differences below.
Bottom line: there is no wrong answer here — match the spec advantages to how you actually use the product. The Mars Score parity says both are well-rounded; the differences are about trade-offs, not quality.
Which should you buy: Huawei - Watch Ultimate or Xiaomi - Watch S4?
Xiaomi - Watch S4 leads the current Mars Score by 4.8 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 Huawei - Watch Ultimate if…
Huawei - Watch Ultimate has the measurable edge on water resistance atm, display size in.
Choose Xiaomi - Watch S4 if…
Xiaomi - Watch S4 has the measurable edge on peak brightness nits, weight g, battery life h.
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 Huawei - Watch Ultimate wins
- ▲Water resistance — 5.00 ATM more. 10 vs 5.
- ▲Display size — 4.90% more. 1.5 " vs 1.43 ".
Why Xiaomi - Watch S4 wins
- ▲Peak brightness — 120.00% more. 2200 nits vs 1000 nits.
- ▲Weight — 32.00 g less. 44 vs 76.
- ▲Battery life — 7.14% more. 360 h vs 336 h.
- ▲Has Cellular.
Spec comparison
Design
| Spec | Huawei - Watch Ultimate | Xiaomi - Watch S4 |
|---|---|---|
| Case size | 48.5 mmlead | 47 mm |
| Weight | 76 g | 44 glead |
| Case material | titanium | stainless steel |
| Water resistanceⓘ | 10 ATMlead | 5 ATM |
Display
| Spec | Huawei - Watch Ultimate | Xiaomi - Watch S4 |
|---|---|---|
| Display size | 1.5 "lead | 1.43 " |
| Always-on display | true | true |
| Peak brightnessⓘ | 1000 nits | 2200 nitslead |
Health & Fitness
| Spec | Huawei - Watch Ultimate | Xiaomi - Watch S4 |
|---|---|---|
| ECG | true | true |
| SpO2 | true | true |
| Temperature sensor | true | true |
| Sleep tracking | true | true |
| Blood pressure | false | false |
Battery & Connectivity
| Spec | Huawei - Watch Ultimate | Xiaomi - Watch S4 |
|---|---|---|
| Battery lifeⓘ | 336 h | 360 hlead |
| GPS | true | true |
| Cellular | false | truelead |
| NFC | true | true |
| OS | HarmonyOS | HyperOSlead |
Frequently asked
Which has longer battery life, Watch Ultimate or Watch S4?+
Watch S4 lasts 360 hours vs 336 hours.
Do Watch Ultimate or Watch S4 support ECG?+
Both support ECG.
Which has cellular, Watch Ultimate or Watch S4?+
Watch S4 offers a cellular variant; Watch Ultimate is Wi-Fi only.