VO2 Max Estimate (Heart Rate Ratio)
VO2 max — the most oxygen your body can use during hard exercise — is measured in a lab with a breathing mask. This page gives a rough estimate using the published heart rate ratio method: VO2 max ≈ 15.3 × max heart rate ÷ resting heart rate. It doesn't convert the number into a "fitness age".
Before you start
Method : Published heart rate ratio equation (Uth 2004), optionally with the Tanaka max-heart-rate formula.
Validation : Arithmetic tested with hand-worked examples. Developed in trained men aged 21–51; untested for other groups.
Review : not reviewed by a qualified clinician. Educational only — not a diagnosis or a medical test.
Not valid if you take beta-blockers or other heart-rate medicines. It cannot assess heart or lung health.
Your answers stay in this browser tab; nothing is sent or stored.
How to Use This Calculator
- Enter your age and resting heart rate (taken sitting quietly in the morning).
- If you know your measured max heart rate, add it; otherwise the Tanaka age formula is used.
- Press Estimate VO2 max.
Methodology & assumptions
VO2 max (ml/kg/min) = 15.3 × HRmax ÷ HRrest (Uth et al. 2004). HRmax is your measured value if you enter one; otherwise the Tanaka estimate 208 − 0.7 × age. No other adjustments are made.
Worked examples
Age 40, resting 60, no measured max: HRmax = 208 − 28 = 180 → 15.3 × 180 ÷ 60 = 45.9 ml/kg/min.
Measured max 190, resting 50: 15.3 × 190 ÷ 50 = 58.1 ml/kg/min.
Understanding your result
Use the number to follow your own trend over time with the same method, not to compare yourself precisely with others. Medicines such as beta-blockers make the estimate invalid.
Sources & further reading
Frequently Asked Questions
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