Xiaomi Watch S4 Review: A Bold, Customizable Smartwatch That Doesn’t Always Deliver

Xiaomi Watch S4 Review: Customization King, But Not Without Flaws

The Xiaomi Watch S4 is one of the most customizable smartwatches on the market today. With a single 47mm case size in silver, grey, or black, it’s not the most size-inclusive option, but it redeems itself with a swappable bezel system and standard 22mm strap compatibility.

Our review unit is the Rainbow edition, featuring a fluororubber strap with vibrant stitching and a colorful bezel — a look that’s both fun and premium. For €170 (often found on discount), this watch undercuts competitors in price while offering premium design touches like a ceramic dual-tone bezel accessory.

Design and Build

The Watch S4 is built with an aluminum alloy case — keeping the weight at just 44.5g, lighter than both the Galaxy Watch6 Classic and OnePlus Watch 3.

It wears large but feels deceptively light, making it ideal for fitness users who want a big display without the wrist fatigue.

The rotating crown is a welcome upgrade, offering smooth scrolling with satisfying haptic feedback. However, the second button isn’t customizable — a baffling omission in such a versatile device.

Display and Always-On Drama

The 1.43-inch AMOLED display is stunning — bright (2,200 nits), sharp (466x466px), and fluid (60Hz). But there’s a catch

. The Always-On Display (AOD) isn’t identical to the main watch face. Instead, each face has a separate AOD variant, often simplified or visually different. This might frustrate those used to Apple or Samsung watches where AOD closely mirrors the active face. Yes, you can preview these AOD versions in the Mi Fitness app — but the inability to mix and match faces and AODs limits true personalization.

Interface and Usability

Xiaomi’s HyperOS 2 powers the Watch S4 with smooth performance and an intuitive (if somewhat basic) UI. Vertical scrolling is the primary navigation, differing from the typical side-swipe interfaces. There are gesture controls — shake your wrist, snap your fingers — but in practice, they work inconsistently and feel gimmicky.

Notifications work well for viewing, but lack replies or emoji support. You’ll see symbols instead of emojis in apps like Messenger — a disappointing oversight in 2025.

Fitness Tracking and Sleep Accuracy

With over 150 sports modes, dual-band GPS, and a surprisingly solid heart rate monitor, the Watch S4 excels in fitness features. GPS locks quickly and maps are accurate.

However, Xiaomi’s sleep tracking needs improvement. It frequently overestimates deep sleep duration, sometimes reporting over 2 hours of deep sleep — highly unlikely based on comparative testing with Galaxy and Huawei trackers. Still, Xiaomi adds flair with sleep animal avatars and sleep score comparisons to other users, which might appeal to casual users.

Battery Life

Xiaomi claims up to 15 days of battery life, but with Always-On Display and full features enabled, expect around 2-3 days. That’s fine for a bright AMOLED screen, but nowhere near the advertised numbers unless you turn off nearly everything fun.

Verdict

The Xiaomi Watch S4 offers fantastic design, display, and customization at an aggressive price. But the AOD quirks, limited button customization, and misleading battery life claims prevent it from being the perfect smartwatch. It’s great — just not quite smart enough yet to dethrone the competition entirely.

Pros:

• Premium look and lightweight feel
• Swappable bezels and 22mm strap support
• Stunning AMOLED screen
• Good GPS and fitness tracking
• Affordable for its feature set

Cons:

• Only one size (47mm) may not suit all wrists
• Inconsistent Always-On Display design
• No button customization
• Sleep tracking accuracy is questionable
• Real-world battery life falls short