COLMI M42 Smart Watch Review: Sleek Design, 100+ Sports Modes and AMOLED at £47

The COLMI M42 sits at the premium end of the COLMI smartwatch family — and it earns that position with a combination of a striking slim profile, a vibrant AMOLED display, a strong battery, and over 100 sports modes. At £47.42, it costs a little more than many entry-level COLMI models, but the experience you get in return justifies the difference. We put the M42 through weeks of daily use across work, sport, and social settings to give you the most thorough assessment possible.

First Impressions: A Watch That Doesn't Look Like a Budget Watch

Take the COLMI M42 out of its packaging and the first word that comes to mind is "refined." The slim, elegant profile immediately distinguishes it from the more traditional budget smartwatch aesthetic. There's no chunky bezel, no chunky case — just a clean, modern design that looks considerably more expensive than £47.

Available in three colours — Green, Silver, and Black — the M42 offers something for different tastes. The Green variant is genuinely distinctive and attention-catching in a subtle way. The Silver and Black options are more versatile, working well across both casual and professional settings. All three use soft silicone straps that feel comfortable against the skin, and the clasp sits flush against the underside of the strap for a neat, jewellery-like finish.

The slimness of the case isn't just aesthetic. A thinner watch is more comfortable under a jacket or shirt cuff, doesn't snag on clothing, and draws less attention in settings where you'd rather your tech remain discreet. For professional environments particularly, the M42's profile is genuinely an advantage over bulkier fitness-focused watches.

Key Specifications

CPU: RTL8763EWE-VP
Screen: AMOLED 1.43 inches, 466×466 resolution
Bluetooth: 5.0
Battery: 410mAh
Waterproof: IP68
Strap: Silicone, 22mm width
Compatible with: Android and iOS
Companion app: DaFit

The AMOLED Display: Vivid, Sharp, and a Pleasure to Use Daily

The M42 uses a 1.43-inch AMOLED panel at 466×466 resolution, and it genuinely looks excellent. AMOLED screens produce deeper blacks, richer colours, and better contrast than IPS alternatives — and at this resolution, watch faces look sharp and detailed with no visible pixellation.

One of the day-to-day benefits of AMOLED that's easy to underestimate is outdoor visibility. Because each pixel generates its own light (rather than a blanket backlight shining through a liquid crystal layer), AMOLED screens are generally more readable in direct sunlight at the same brightness setting as an IPS screen. If you spend time outdoors, this translates to fewer moments of tilting your wrist at an awkward angle to read the display.

The touchscreen response is smooth and accurate throughout our testing — no missed taps, no laggy swipes, no need to press harder than you'd expect. Everything feels responsive and intuitive, contributing to the overall sense that the M42 is a watch that performs above its price point.

Watch Faces and Personalisation

The M42 comes with a solid selection of pre-installed watch faces, ranging from traditional analogue designs to modern digital layouts with health metrics displayed directly on the home screen. Through the DaFit companion app, you can browse and download additional watch faces to keep things fresh.

The AMOLED display makes high-quality watch faces look particularly good — designs with dark backgrounds especially benefit from the true blacks and vivid accent colours that AMOLED produces so well. On the Green variant, a watch face using complementary emerald tones creates a genuinely striking combination that's hard to achieve with an IPS-screen watch.

Battery Life: Impressive for an AMOLED Watch

One of the most common trade-offs with AMOLED smartwatches is battery life — the vivid display technology draws more power than IPS at equivalent brightness levels. The M42 handles this particularly well, thanks to its 410mAh battery, which is larger than many competitors in the AMOLED smartwatch category.

In our testing with the display brightness set to a moderate level, continuous heart rate monitoring active, sleep tracking enabled, and notifications coming through regularly, the M42 consistently achieved 10–12 days of battery life between charges. That's exceptional for a watch with an AMOLED screen at this price.

For comparison, the COLMI i28 Ultra (also AMOLED, also 466×466) uses a 260mAh battery and achieves around 7–10 days. The M42's 410mAh cell gives it a meaningful battery life advantage while offering the same display quality.

Charging from flat takes approximately 1.5–2 hours via the included magnetic charging cable. The magnetic connection is reliable and snaps cleanly into place — no fumbling required.

Health and Fitness Monitoring: Comprehensive Coverage

The M42's health monitoring suite covers all the metrics you'd want from a modern smartwatch:

Heart Rate Monitoring

Continuous 24/7 optical heart rate monitoring using the sensor on the underside of the case. The data is stored in the DaFit app, where you can review both real-time readings and historical trends. In our testing, resting heart rate readings were consistent and reliable, with active exercise readings performing well for moderate-intensity activities.

Blood Oxygen (SpO2)

On-demand blood oxygen monitoring using the optical sensor. Regular SpO2 checks provide insight into how well your body is oxygenating — useful both during exercise and for monitoring overnight recovery quality.

Sleep Tracking

The M42 automatically detects sleep onset and monitors your sleep stages throughout the night, including light sleep, deep sleep, and wake periods. The DaFit app presents each night's data as a visual timeline along with a sleep quality score, making it easy to assess and track sleep quality over time. The IP68 waterproof rating means you don't need to remove the watch before a bath or shower — but many users do still remove it for bed. If overnight health monitoring is a priority, consider pairing the M42 with a COLMI smart ring for more comfortable overnight tracking.

Stress Monitoring

Using heart rate variability (HRV) analysis, the M42 estimates stress levels throughout the day. Many users find this feature genuinely revealing — identifying periods of elevated stress they weren't consciously registering, and helping them build awareness of their own stress patterns over time.

Step Counting and Activity Metrics

Daily steps, estimated distance, and calories burned are tracked automatically. Progress toward daily goals is displayed on the watch face and in the app dashboard, making it easy to see at a glance whether you're on track for the day's activity target.

Menstrual Cycle Tracking

The companion app supports cycle logging and prediction for female users, integrating this data alongside other health metrics for a more complete health picture.

Sports Modes: 100+ Activities Covered

The M42 includes over 100 dedicated sports modes, covering the full spectrum from common activities like running, cycling, and swimming to more specialised options like rowing, rock climbing, and dance fitness. To start a workout, simply navigate to the sports section from the main menu, select your activity, and press start.

Each sports mode tracks the relevant metrics for that activity. For running: pace, distance, heart rate, and calories. For cycling: speed, distance, heart rate, and calories. For swimming: laps, distance, heart rate, and calories. The data syncs to the DaFit app after each session, where you can review your performance history and progress over time.

The IP68 waterproof rating means the M42 is genuinely suitable for swimming. This is meaningful at this price point — not all budget smartwatches can handle full immersion, and the M42 doesn't just claim waterproofing but delivers it to the IP68 standard, which covers submersion up to 1.5 metres for 30 minutes.

Note: Like most COLMI watches in this price range, the M42 uses connected GPS (your phone's GPS) rather than built-in GPS for outdoor route tracking. For standalone route tracking without your phone, look at the COLMI V75 GPS or COLMI V76 GPS.

Smart Notification Features

Paired to your smartphone via Bluetooth 5.0, the M42 handles notifications cleanly. Call alerts vibrate the watch and display the caller's name on screen. Messages from SMS, WhatsApp, email, and most major apps appear as previews on the watch face. Music playback control lets you manage your playlist from your wrist during workouts or commutes.

The companion DaFit app lets you configure exactly which apps send notifications to the watch, so you can filter out less important alerts and keep your wrist free from notification overload.

How the M42 Compares to Other COLMI Smartwatches

vs COLMI i28 Ultra (£42.28): Same AMOLED display quality, but the M42 has a larger 410mAh battery (vs 260mAh), making it the better choice if battery life is your priority. The i28 Ultra wins on colour options and has a magnetic strap option.
vs COLMI V73 (£34.73): The V73 is more affordable and also offers AMOLED, but the M42's larger battery and slimmer, more premium design justify the price difference for users who value aesthetics and longevity between charges.
vs COLMI P86 (£44.86): The P86 offers a curved AMOLED display and a more sporty aesthetic; the M42 prioritises slim elegance and longer battery life.
vs COLMI V75 GPS (£44.75): The V75 adds built-in GPS — a significant advantage for outdoor runners and cyclists. If route tracking matters to you, the V75 is worth the premium.

What We Liked

Slim, elegant design that looks far more expensive than £47
Outstanding AMOLED display — vivid, sharp, and easy to read
Exceptional battery life for an AMOLED watch (10–12 days)
Comprehensive health monitoring suite
IP68 waterproof for swimming and showering
100+ sports modes
Three attractive colour options including the distinctive Green
Smooth, responsive performance throughout

What Could Be Better

No built-in GPS (uses connected GPS via phone)
Bluetooth 5.0 rather than the newer 5.3 in some comparable models
Only two strap options (standard silicone — no magnetic strap alternative)

Who Is the COLMI M42 Best For?

The M42 is an ideal choice for:

Style-conscious buyers who want a slim, premium-looking smartwatch without paying premium prices
Users who want an AMOLED display but also need strong battery life between charges
People who work in professional environments where a subtle, elegant watch is more appropriate than a fitness-focused device
Regular gym-goers and swimmers who want health and fitness tracking in a stylish package

Our Verdict

The COLMI M42 is one of the best-looking smartwatches in the entire COLMI range — and it backs that appearance up with genuine performance. The slim design, beautiful AMOLED display, exceptional battery life, and comprehensive health tracking make it feel like a much more expensive product. At £47.42, it represents outstanding value for a smartwatch that genuinely delivers on every front.

If you want a watch that performs reliably, tracks your health thoroughly, and looks great on your wrist every single day — the M42 is a very strong choice.

👉 Buy the COLMI M42 Smart Watch — £47.42