Apple Watch Readiness score explained: what it measures, and why only Series 12 and Ultra 4 get itApple Watch Readiness score explained: what it measures, and why only Series 12 and Ultra 4 get it

Readiness, Apple's new daily score of how prepared your body is for exertion, works only on Apple Watch Series 12 and Apple Watch Ultra 4.

Apple's support document, published on 14 September, describes it as a score from 0 to 10 in four bands: Recover from 0 to 1, Pace Yourself from 2 to 4, Ready from 5 to 7, and Go for it from 8 to 10. It appears in its own Readiness app on the watch and in a Readiness tab in the Fitness app on iPhone. Apple's user guide says the feature is for people aged 13 and over. iClarified published an explainer on 1 October, and Apple's two documents are the primary source for everything below.

What goes into the score?

Apple lists three groups of inputs, each compared against your own recent baseline:

• Activity: calories, workout effort and Training Load
• Vitals: heart rate, respiratory rate, wrist temperature, heart rate variability and blood oxygen, by day and overnight
• Sleep: recent sleep scores and sleep history

The score is set in the morning and then updates during the day from calories burned, naps and daytime heart rate. Apple calls it a general wellness feature and says it does not account for existing conditions or medication.

How do you set it up?

Four things must be in place first: a health profile with height, weight and age in the Fitness app, Activity, a sleep schedule, and Overnight Vitals. The watch needs to have been worn to bed on at least seven of the past 49 nights, and Apple's support document adds that it must have been worn the night before. A new owner should expect a week before the first score appears.

Why does an older Apple Watch not get it?

Apple's documents list only the two new models and give no reason. iClarified confirms that Series 11 and earlier, Ultra 3 and every SE model are excluded. Several outlets tie the limit to the new sensing hardware in this year's watches, which reportedly samples heart rate and variability more often, but Apple's documents do not say so. The same pair of watches has already parted ways with older models elsewhere: Series 12 and Ultra 4 dropped handwashing detection, so the new hardware both gains and loses features.

Our take

Readiness is Apple arriving where Whoop, Oura and Garmin have been for years, and its design is sensible: a small number of bands, plain language, and a score that moves with naps rather than being fixed at breakfast. The requirement for seven nights in seven weeks is lenient compared with rivals that want nightly wear.

The model limit is the harder sell. Most of the inputs, heart rate variability, wrist temperature, sleep, Training Load, were already measured by last year's watches. APPDOOK's reading is that Apple may be right that better sampling makes a better score, but it has not said so, and owners of a one-year-old Series 11 are entitled to the reason. For anyone choosing between models, our Apple Watch SE 3 or Series 12 guide now has one more line on the Series 12 side.