ScanWatch 2 42 mm Blue a 35-day health watch that hides its tech

What is new about the ScanWatch 2 42 mm Blue?

The ScanWatch 2 itself is not new. Withings launched it in 2023 as a hybrid: real hands over a real dial, with a small greyscale OLED window and a set of health sensors hidden underneath. What arrived on 5 September 2025, announced at IFA in Berlin, was a refresh. Withings added a 42 mm version with a blue sunray dial on a silver steel case, plus a new operating system called HealthSense 4.

Withings says HealthSense 4 tracks 35 health measures. The headline additions are REM sleep detection, overnight breathing rate, better step counting and a "Vitality Indicator" that combines heart rate variability, temperature, blood oxygen, breathing and sleep into an energy score. The watch can also send alerts when its temperature data suggests the start of a menstrual cycle or a possible infection. Quoted battery life rises from 30 to 35 days.

One thing to note: the Vitality Indicator is a Withings+ feature, and Withings+ is a paid subscription. Withings bundles a free trial with the watch, but after that you pay monthly or yearly to keep it.

How big is it, and how will it wear?

Withings lists the case at 42 mm, with thickness between 12.89 mm and 13.39 mm across the two ScanWatch 2 sizes. That puts it in normal everyday watch territory. It is smaller and slimmer than most touchscreen smartwatches, and it looks like a sports watch rather than a gadget.

The strap is an FKM (fluoroelastomer) rubber band in a matching blue. It swaps without tools, and Withings sells leather, woven and metal alternatives. Digital Trends found the supplied strap awkward to size, with one hole too tight and the next too loose, and fixed it by fitting a 20 mm rubber strap from another watch. If you sit between sizes, budget for a second strap.

What movement does it use, and how accurate is it?

This is a smart watch, so there is no mechanical movement to judge. The hands are driven by motors and set themselves from your phone over Bluetooth, so timekeeping is not a concern. The more useful accuracy question is about the health data.

Withings describes the ECG as medical grade, and it is the main reason people buy a ScanWatch. A 30 second reading taken by touching the bezel can flag signs of atrial fibrillation. Alongside that you get blood oxygen, 24/7 heart rate, skin temperature tracking, elevation tracking and connected GPS through your phone.

Independent reviewers are more mixed on everyday tracking. Coach found step counts close to a Garmin, with a slight tendency to undercount, but heart rate during runs often read high, and auto detection once logged a pushchair walk as a bike ride. Digital Trends saw sleep split into a nap plus a short night on some occasions. HealthSense 4 promises better sleep staging and step counting, so some of this may improve, but it is worth knowing before you buy.

How well is it built?

The basics are solid for the money. The case is stainless steel, the crystal is sapphire, and Withings rates it to 5 ATM (50 m), which it calls swimproof. Withings says a full charge takes about two hours.

Battery life is the stand out. Withings quotes 35 days, and Coach reported charging just once in six weeks of fairly heavy use on the earlier software. Coach also noted that breathing tracking, notifications and manually logged workouts cut that down, with heavy workout logging bringing it closer to 10 to 15 days.

Is it good value against its rivals?

The RRP for the 42 mm Blue is £319.95 on Withings UK. Withings has discounted the ScanWatch 2 range at times, so it is worth watching for offers, but the RRP is the fair comparison point.

The closest rival is Garmin's vivomove Trend, a hybrid with hidden displays that launched in the UK at £279.99. It is better for workouts and adds Garmin Pay, but it has no ECG and its battery life is measured in days, not weeks. Within Withings, the ScanWatch Light at £229.95 drops the ECG and blood oxygen sensors, while the ScanWatch Nova at £549.95 gives you a dive style bezel and a steel bracelet with the same sensors.

If ECG and long battery life are the priority, the ScanWatch 2 is the cheapest way to get both in a watch that does not look like a smartwatch.

What is the catch?

The catch is the gap between the watch and the app. The hardware is neat and the battery is excellent, but the most interesting new feature sits behind a subscription. Workout heart rate has been patchy in independent reviews, and smart features are limited to notifications on a tiny screen: no apps, no payments, no voice assistant. Buy it as a health monitor that looks like a proper watch, not as a fitness watch or phone replacement.

“A health monitor that looks like a proper watch, not a phone on your wrist.”

What do owners say?

Themes from public owner feedback, paraphrased. We never copy Amazon reviews or ratings.

• Long-term users of the original ScanWatch 2 found the supplied strap hard to size and sleep tracking occasionally split a night into a nap and short sleep

  Digital Trends (opens in a new tab)

• Battery life holds up in real use, with one charge in six weeks reported on the earlier software

  Coach (opens in a new tab)

• Workout heart rate on runs often reads high, and auto activity detection can mislabel sessions

  Coach (opens in a new tab)