OPPO Watch S Review 2026 – Ultra-Slim 35g Smartwatch with 3000-Nit Display & ECG

By Omar Shahid, Tech Writer — March , 2026

The OPPO Watch S is the company's latest smartwatch, sitting comfortably in the mid-range segment but punching way above its weight class in a few key areas. It launched globally in early 2026 with a simple mission: deliver flagship-level health tracking in a body that doesn't feel like a brick strapped to your arm. The name? Pretty sure the "S" stands for Slim. And honestly, they earned it.

At 35g and 8.9mm thick, this is the smartwatch that disappears on your wrist. After wearing heavy smartwatches for years, putting on the Watch S feels like putting on nothing at all.

At a Glance

Design: The 35g That Changes Everything

Within about 48 hours, the Watch S quietly worked its way into daily routine without being noticed. That is the point. It is not about flashy gimmicks or specs that look impressive in a press release. It is about a device that disappears on your wrist — until you need it. 

The Watch S features a sleek metal body that is just 8.9mm thick and weighs a mere 35g — roughly a quarter thinner and lighter than its predecessor. The stainless steel case measures 44.98mm. 

For sleep tracking, everyday wear, and exercise — a lighter smartwatch is simply a better smartwatch. You will wear it to bed without thinking about it. You will forget it is on your wrist during workouts.

Display: 3000 Nits. In a Smartwatch.

The OPPO Watch S packs a 1.46-inch AMOLED panel that hits a peak brightness of 3,000 nits. Most smartwatches claim outdoor visibility. The Watch S delivers it. Testing it during a noon run on a cloudless summer day — direct sunlight, zero shade — the display was crystal clear. That 3,000-nit mode only kicks in automatically during outdoor workouts to save battery. Normal usage tops out at 1,500 nits, which is still brighter than most competitors.

3000 nits peak brightness puts the Watch S on par with the Apple Watch Ultra 3 for outdoor display performance. At €259, achieving that brightness milestone is extraordinary.

The 60Hz refresh rate keeps animations smooth. 350+ watch faces are available through the ColorOS Watch app.

Health Sensors: The Full Premium Package

Health monitoring employs an 8-channel heart rate sensor, a 16-channel blood oxygen sensor, and wrist temperature sensor. Standard heart rate and SpO2 sensors, a dual-frequency GPS module for outdoor tracking, and an NFC chip for contactless payments complete the array. 

On the health front, the Watch S is a major step up, incorporating an ECG and a skin temperature sensor for the first time in the line. 

The ECG feature enables clinically meaningful heart rhythm analysis. Skin temperature tracking provides trend data for early signs of illness. The dual-frequency GPS — using both L1 and L5 signals — produces more accurate location tracking than the single-frequency GPS in most competing smartwatches at this price.

Sports and Fitness

Fitness capabilities span over 100 workout modes with tailored parameters. Running features include guided training, posture analysis, and lactate threshold tracking. Professional court analytics enhance specific sports modes with detailed performance data. 

Lactate threshold estimation — previously reserved for high-end sports watches costing $400–600 — at €259 is a significant value proposition for serious runners and cyclists.

Battery Life: The Real-World Numbers

The OPPO Watch S packs a 330mAh battery that can last up to ten days in power-saving mode, four days with always-on-display active. In real-world testing, approximately six days were achieved between charges. A quick charge while in the shower works well and provides enough for a few more days. 

Six days real-world is the honest expectation. For comparison: Apple Watch Series 11 requires daily charging. Samsung Galaxy Watch 8 lasts approximately 2 days. The Watch S's endurance advantage is significant for users who travel or dislike frequent charging routines.

What It Lacks: The Honest Trade-offs

There is no app store for the OPPO Watch S. It runs OPPO's own ColorOS Watch 7.1, which is not part of the Android Wear platform. The NFC chip can only be used for cloning access cards, not for mobile payments. By omitting a full Wear OS ecosystem and eSIM, OPPO has prioritised achieving an ultra-sleek design, excellent battery life, and advanced health sensors. 

This is the fundamental trade-off: the Watch S is not a mini-smartphone for your wrist. It is a health and fitness tracker with a brilliant display and outstanding battery life. If you want third-party apps, Spotify streaming, or contactless payments — look at a Wear OS watch. If you want something you forget you are wearing that accurately tracks your health — the Watch S is compelling.

Full Specifications

Pros and Cons

Verdict

The Watch S strikes a specific balance between a "smart" watch and a "traditional" watch. It is an excellent choice for users who prioritize health metrics, enjoy various sports, and primarily need a watch for notifications and timekeeping. The 3000-nit screen and built-in ECG offer tremendous value at this price point. However, it is not the best fit for tech enthusiasts or power users who rely on third-party apps.

Rating: 8.5/10 — If you value fitness tracking, battery life, and wearing a watch that actually feels like a watch — the OPPO Watch S at €259 is the best value proposition in its class.