Apple Watch Ultra 4

The Apple Watch Ultra 4 is an inside-out upgrade. The rugged titanium design is unchanged from previous generations, so the story here is the redesigned Health Sensing System. Apple says its more capable optical and electrical sensors and larger, more power-efficient green LEDs are meant to deliver more frequent and more accurate health readings.

The watch is aimed at people who want a tough smartwatch with serious health and training insight. A new Readiness score advises whether to rest or train, and more frequent HRV readings feed stress and recovery insights. That makes it a natural fit for endurance athletes, divers and outdoor enthusiasts already in Apple's ecosystem.

At £749, it is a premium purchase. Whether it is worth that money depends heavily on what you are wearing now.

On paper, the Ultra 4's priorities are the right ones. Apple rates it at up to 50 hours of normal use, the longest of any Apple Watch, and fast charging adds up to 18 hours of use in 15 minutes. It keeps the durability credentials that define the Ultra line: sapphire crystal, WR100 water resistance, IP6X dust resistance and MIL-STD-810H testing.

The new sensor system is the main reason to buy. Apple backs the optical heart rate sensor with a study of 1,400 people, most of whom wore competitor watches at the same time. That is an encouraging sign, but it is Apple's own research. Independent testing is more mixed: Trusted Reviews found heart rate tracking was not spotless.

Software timing is the bigger caveat. Some Audio Intelligence features and the redesigned Health app with Health Age won't arrive until late 2026. Buyers are partly paying for promises that aren't yet delivered. The new sensors also add a gram of weight, which is trivial but shows the hardware gains are internal rather than visible.

Overall, this is a strong, refined rugged smartwatch for buyers coming from older models or other platforms. For Ultra 3 owners, the unchanged design, imperfect heart rate results and delayed software make an immediate upgrade hard to justify. That supports a solid but not outstanding rating.