Recap: Apple Watch Series 12 and Ultra 4 add a redesigned health sensor

Apple has refreshed its watch line-up with the Apple Watch Series 12 and Apple Watch Ultra 4, and the biggest changes are under the skin rather than on the outside.

Both models use Apple’s new S11 chip — not S12 — alongside a redesigned Health Sensing System. Apple says the new setup allows more frequent heart-rate and heart-rate variability measurements, with a new readiness score designed to give a clearer picture of how prepared you are for exercise or a busy day.

Series 12 starts at £369 in the UK, while Apple Watch Ultra 4 starts at £749. Both are available to pre-order now and go on sale on 18 September.

The Ultra 4 remains the more rugged option, with up to 50 hours of everyday battery life, while Series 12 is rated for up to 24 hours. Both also get Siri AI with watchOS 27, while Apple says new Audio Intelligence features will arrive later in the year.

There are some cosmetic changes too. Series 12 adds new aluminium and titanium finishes, plus ceramic versions in pearl white and night blue. Ultra 4 continues in natural and black titanium.

The health changes look more meaningful than the usual annual processor bump, but we’ll need to see how useful the readiness score and more frequent background readings prove in everyday use.

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