Titan Age brings your sleep, daily movement, training, and fitness into one view of your progress. Compare your estimate with your actual age, explore the 11 signals behind it, and follow how they change from week to week. You can see the contribution of each signal, from consistent sleep to the workouts you record.
01Read your Titan Age
Titan Age shows how your estimate has changed and which health measurements contribute to it.
Tap the Titan Age card on Today to open the full view. Under the number, Titan states how many years younger or older than your actual age the estimate sits. The dial places your Titan Age against your actual age, which sits at the center line. Green means younger and red means older. Short marks inside the arc show your last 12 weeks. The line under the dial compares this week with four weeks earlier, for example "Down 1.2 years in 4 weeks".
Each contributor shows a health measurement and its effect on Titan Age, expressed in years. A negative contribution subtracts years from the estimate. A positive contribution adds years. For example, a sleep contribution of -1.0 means your sleep data lowers the estimate by one year, and the row reads "1.0 years younger". Within each group, the rows with the largest effect come first, and every bar shares one scale.
Tap a row to expand it. You see Neutral, the value at which that signal adds no years. A row without enough days of data shows a count such as "0 of 4 days" in grey. It still counts, and its expanded view adds Counted at, the value Titan used in its place. Recorded VO2 Max and heart rate recovery rows add a fitness rating. VO2 Max is rated against norms for your age and sex. The rating does not change the years.
Titan Age covers your last completed week, Monday through Sunday. A new estimate appears once the week closes, giving you a consistent period to compare as your history grows.
0211 contributors
Recovery brings together your sleep pattern and heart rate at rest and after exercise. Resting heart rate, sleep duration, two-minute heart rate recovery, and sleep consistency contribute 46% of the model.
Activity shows the contribution of everyday movement and recorded training. Weekly steps, Zone 2 minutes, Zone 4+ minutes, strength minutes, and stand hours contribute 35% of the model.
Fitness adds aerobic fitness and body composition to the picture. VO2 Max and lean mass index contribute the remaining 19% of the model.
Each weight is the signal's share of the whole model, rounded as the app shows it. Rounded row percentages may not add to the group total.
| Group | Signal | Weekly measure | Weight |
|---|---|---|---|
| Recovery, 46% | Resting heart rate | Daily average, needs 4 days | 18% |
| Sleep | Nightly hours averaged, needs 4 nights | 12% | |
| Heart rate recovery (2 minutes) | 2-minute estimate on workout days, needs 2 | 10% | |
| Sleep Consistency | Daily average, needs 4 days | 7% | |
| Activity, 35% | Weekly Steps | Weekly total, needs 4 days | 9% |
| Zone 2 Minutes | Weekly total, 1 day counts | 8% | |
| Zone 4+ Minutes | Weekly total, 1 day counts | 8% | |
| Strength Training | Weekly minutes, 1 day counts | 5% | |
| Stand Hours | Daily average, needs 4 days | 5% | |
| Fitness, 19% | VO2 Max | Latest reading in the past 30 days | 16% |
| Lean Mass Index | Latest in the past 30 days | 3% |
The total for Recovery, Activity, or Fitness shows how many years that group's contributors add or subtract together. For a view of today's training readiness, see your daily Recovery score.
03Age history and pace
The Age history chart plots one Titan Age per week. Choose 4 Weeks, 12 Weeks, or 6 Months. Latest in period is the newest week's Titan Age, and Change in period is the newest week minus the first. A break in the line marks a week with no estimate.
Select any week on the chart to read its Titan Age and Pace. Pace is a percent that shows how quickly your Titan Age is changing, based on up to 52 weeks of history. Titan averages the weekly changes into a yearly rate, then expresses that rate as a percent of the week's Titan Age. A negative pace is the favorable direction. If your Titan Age falls 0.02 years each week at a Titan Age of 35, the yearly rate is about -1 year and pace reads -3.0%.
04Missing data
A signal short of its minimum days counts as missing. Titan can still calculate an estimate using the available signals and your history. Check that Apple Health has your date of birth, that your tracker is recording, and that Titan can read the relevant categories. Set up Apple Health for Titan walks through those checks. For a blank or stuck card, see Titan Age missing or not updating.
05How Titan Age is calculated
Calculation details on the Titan Age screen lists each signal's value, contribution in years, target, weight, and days of coverage for the week. Target is the same value the rows call Neutral. The steps below explain how those numbers are produced.
Titan starts from your actual age at the end of the completed week, using your date of birth in Apple Health. It then calculates the contribution of each signal before smoothing the result and applying any adjustment for existing history.
Calculating each contribution
Each signal has a reference value and a step size. Titan measures how many steps your week sits from the reference, then softens that distance so very large gaps add less than a straight line would. The result is multiplied by 6 years, the signal's weight, and a coverage factor.
Take resting heart rate. The reference is 80 bpm and the step is 5 bpm. A week averaging 60 bpm sits four steps better than the reference. After softening and weighting, with full coverage, that lowers Titan Age by about 1.7 years.
The coverage factor is based on the weighted share of the model you recorded that week. Missing signals lower it and shrink every signal's effect.
When a signal is missing, Titan fills it with the median of your recorded weeks from the past 26, once you have at least 6. With less history, Titan uses the reference value, which adds zero years. Weekly totals are scaled up to a full week from the days recorded, and any week with fewer than 3 recorded days is treated as 3.
Apple Watch records heart rate recovery at one minute. Titan multiplies that value by 1.65 to estimate the two-minute drop and keeps the result between 10 and 70 bpm. Lean Mass Index is lean body mass in kilograms divided by height in meters squared. Titan calculates lean body mass from weight and body fat percentage. See heart rate zones and sleep consistency for how those signals are counted.
Why Titan Age changes gradually
Titan smooths each new weekly result against the previous week's calculated age. The update moves between 18% and 62% of the way toward the new result. Better coverage and a history of larger weekly swings move it faster. Sparse data and a steady history move it slower.
When saved estimates from the previous model are available, Titan also applies a fixed adjustment across the calculated history. It aligns the most recent week shared by both models with its saved estimate, preserving continuity with your existing history. Without that history, the adjustment is zero.
Smoothing and this history adjustment mean the signal contributions for one week do not add up exactly to the gap between the displayed Titan Age and your actual age.
To calculate Pace, Titan takes each week-to-week change from up to 52 weeks of Titan Age, lightly averages each one with its neighbors, and converts the average into years of change per year.
What the estimate can tell you
Titan Age is a model estimate calculated from your recorded health data. Use it to follow your own direction over weeks and months. It is not a clinical measurement of biological age, and the model's reference values are not personal training or health targets.
