Apple has unveiled new health features with the release of the Apple Watch Series 12 and the Ultra 4, announced on September 9, 2026. One of the most notable additions is an updated Health app that includes a feature called "health age." This feature uses data collected by the Apple Watch to estimate how a user’s health compares to the typical health profile of someone at their actual age. The company says the goal is to help users understand their health trends over time and make more informed lifestyle choices. The new "Longevity" tab in the Health app compiles data from several key health indicators, such as heart health, sleep quality, mental well-being, physical activity levels, metabolism, hearing, and nutrition. The "health age" function compares metrics like VO₂ max (a measure of aerobic fitness), resting heart rate, heart rate variability, sleep patterns, and blood markers such as LDL cholesterol and glycated hemoglobin to averages for the user’s age group. The app then identifies factors that may be affecting the result and offers personalized recommendations through Apple Intelligence, an AI system designed to enhance user experience. The Apple Watch Series 12 improves on previous models by monitoring the user’s body more frequently. It checks the pulse every five seconds and measures heart rate variability up to 24 times more often than earlier versions. A new feature called the "readiness score," which ranges from 0 to 10, combines data on sleep, recent physical activity, and physiological metrics to indicate whether the body is prepared for physical exertion or needs rest. This score can change dynamically throughout the day as new data is collected. Additionally, the Health app now uses the iPhone’s camera to guide users through exercises that assess balance, flexibility, strength, and movement. If the app detects any weaknesses, it can recommend specific programs to help users improve their physical condition. Despite these advancements, some experts remain cautious about the accuracy of wearable health devices. Hunter Bennett, an associate professor in exercise and sports sciences, notes that these tools may not always provide precise measurements for metrics like calories burned, steps taken, heart rate, or sleep quality. Apple acknowledges that "health age" is an estimate based on several indicators and not a complete measure of overall aging. The company emphasizes that the feature is designed to highlight potential health concerns, such as poor sleep or declining physical fitness, and encourage users to take proactive steps toward better health.