Refurbished Tech Buying Guides UK » watchOS 27

Apple Watch Series 12 adds the S11 chip, Readiness, improved heart-rate and HRV sensing, Siri AI, tougher Ceramic Shield 2 and faster short charging. But Series 11 already offers a 2,000-nit Always-On display, 24-hour battery, 5G, ECG, sleep score and watchOS 27. Here’s which offers better value.

Which Apple Watches support watchOS 27? See the full compatibility list, learn which older Series, SE and Ultra models miss the update, understand Apple Intelligence requirements and compare the best refurbished Apple Watches to buy in 2026.

Apple Watch Ultra 4 brings longer battery life, the S11 chip, new health sensing, Readiness and Siri AI — but Ultra 3 already offers the same rugged 49mm titanium design, bright display, 5G, satellite connectivity and serious sports features. Here’s which offers better value in 2026.