In short: lifespan is how long you live; healthspan is how long you stay healthy. A healthspan score rates the measures that large studies link to both: cardiorespiratory fitness (VO2 max), resting heart rate and heart-rate variability, how much you move, how well and how regularly you sleep, and how fast you walk. Fitness carries the most weight. A good score compares you to people your age, and to your own baseline.
Healthspan vs lifespan
Medicine has added years to life faster than it has added healthy years. The idea behind healthspan is to focus on the second: staying strong, mobile and independent for as long as possible. Most of what predicts it can be measured, and much of it can be improved.
What the research says matters most
Cardiorespiratory fitness (VO2 max). Among the everyday measures, fitness is one of the strongest predictors of how long people live. In a study of more than 120,000 adults who did treadmill tests (Mandsager and colleagues, JAMA Network Open, 2018), higher fitness went with lower mortality at every level, with no upper limit where the benefit stopped. An Apple Watch estimates VO2 max from outdoor walks, runs and hikes.
Resting heart rate and heart-rate variability. A lower resting heart rate, and higher heart-rate variability (HRV), the small beat-to-beat variation that reflects how well your nervous system recovers, are both linked to better cardiovascular health.
Daily steps. Large studies have linked more daily steps with lower mortality. The benefit rises steeply from a low base and levels off somewhere around 6,000–8,000 steps a day for older adults and 8,000–10,000 for younger ones.
Sleep, and its regularity. Seven to nine hours is the usual recommendation for adults. Regularity matters too: in a study of over 60,000 people (Windred and colleagues, 2024), going to sleep at a regular time predicted mortality more strongly than sleep duration did.
Walking speed. How fast you walk is a simple marker of overall health in older age; slower habitual walking speed goes with shorter survival (Studenski and colleagues, JAMA, 2011).
Heart-rate recovery. How quickly your heart rate drops after exercise is another signal of cardiovascular fitness (Cole and colleagues, New England Journal of Medicine, 1999).
Why age matters in the score
A resting heart rate of 60 or a VO2 max of 40 means something different at 25 than at 65. A useful healthspan score grades each measure against people of your age (and, for some measures, sex), so a 60-year-old isn’t scored as if they were 30.
Compare yourself to yourself, too
Population averages tell you where you stand; your own baseline tells you what’s changing. A short night, a cold coming on or a hard training block shows up as a drift away from your normal long before it moves a population percentile. The most useful picture combines both.
How Drift does it
Drift is an iPhone and Apple Watch app that reads your Apple Health data and scores it on your device. It gives you two complementary views:
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The Longevity Score (0–100) grades eight pillars against your age group, weighted by the strength of the evidence:
Pillar Weight VO2 max 20% Heart-rate variability 18% Resting heart rate 15% Sleep 15% Daily steps 12% Exercise 10% Heart-rate recovery 5% Walking speed 5% VO2 max is graded against published fitness percentiles for your age and sex. The score is a 14-day rolling average, so one bad day doesn’t swing it. The research behind each pillar links that measure to health and mortality in large groups of people; the weights are Drift’s own model, not a validated formula. From six of the measures (VO2 max, resting heart rate, HRV, sleep, walking speed and exercise) Drift also estimates a biological age: a directional approximation, not a clinical or epigenetic test or a prediction of how long you’ll live.
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The daily Drift Score compares today with your own baseline for the same weekday, across 60+ metrics from Apple Health, and shows how aligned you are with your normal. It needs about four weeks of history to calibrate, which your existing Apple Health history can supply on day one.
Around those sit a Sleep Score (duration, regularity, deep sleep and continuity), a Bedtime Window with a 14-night regularity challenge, a Fitness Score built on training load and intensity, Sun Exposure based on the UV index, and pattern detectors that flag things like a creeping resting heart rate or a run of short nights. An Apple Watch app and complications keep it on your wrist.
Everything is computed on your iPhone and Apple Watch, with no account and no analytics. Scores describe your data and trends; they aren’t a diagnosis or medical advice.
Common questions
What is the difference between healthspan and lifespan?
Lifespan is how long you live. Healthspan is how many of those years you spend in good health, free of serious disease and able to do what you want to do.
What is the best single predictor of healthspan you can track?
Cardiorespiratory fitness, usually measured as VO2 max, is one of the strongest. In large studies higher fitness was linked to lower mortality at every level, with no point where the benefit stopped.
How many steps a day do you need for longevity?
Large studies show the benefit rising steeply from a low base and levelling off around 6,000–8,000 steps a day for older adults and 8,000–10,000 for younger adults.
Does sleep regularity matter as much as sleep length?
It may matter more. In a study of over 60,000 people, regular sleep timing predicted mortality more strongly than sleep duration did. Going to bed at a similar time every night, weekends included, is a simple habit to work on.
Can an Apple Watch estimate my biological age?
Apps can estimate one from measures like VO2 max, resting heart rate, HRV, sleep and walking speed, as Drift does. Treat it as a rough summary of how your measures compare to your age group, not a clinical or epigenetic test.