A rough, non-exercise estimate of aerobic fitness from your resting and max heart rate — no treadmill test needed.
VO₂ max ≈ 15.3 × (HRmax / HRrest) (Uth et al. 2004). The result is then placed on ACSM/YMCA-style fitness bands for your sex and age. A ballpark from two heart rates — not a treadmill test.
Leave blank to use the age estimate (220 − age).
This heart-rate-ratio estimate is a rough approximation — it was validated mainly in young, moderately-trained men, and real aerobic fitness is best measured with a lab or field exercise test. Age-estimated max heart rate (220 − age) also has a wide individual error margin. Treat this as a ballpark, not a lab result.
Formula: Uth, Sørensen, Overgaard & Pedersen, Eur J Appl Physiol 2004 (Heart Rate Ratio Method). Fitness bands: widely used ACSM/YMCA-style normative tables.
The Heart Rate Ratio method estimates VO2 max from just two numbers — your maximum and resting heart rate — using the formula VO2 max ≈ 15.3 × (HRmax / HRrest), a published estimation method from research by Uth et al. (2004).
Your estimated VO2 max is then placed on ACSM/YMCA-style fitness classification bands specific to your sex and age group, giving you a sense of where your cardiovascular fitness sits relative to typical population norms rather than just a raw, uncontextualized number.
This is a ballpark estimate from two easily measured heart rate numbers, not a substitute for an actual treadmill or lab-based VO2 max test, which directly measures oxygen consumption during graded exercise. Use this for a quick general estimate and rough tracking over time, not as a precise clinical or athletic performance measurement.
It's a reasonable ballpark estimate based on published research (Uth et al. 2004), but it's not as precise as an actual treadmill or lab-based test that directly measures your oxygen consumption during graded exercise. Use it for general tracking, not exact performance benchmarking.
Just your maximum heart rate and your resting heart rate — both are used together in the Heart Rate Ratio formula to estimate VO2 max.
They compare your estimated VO2 max against ACSM/YMCA-style reference ranges specific to your sex and age group, giving general context for where your cardiovascular fitness sits — not a personalized clinical or athletic assessment.
Measure your pulse first thing in the morning before getting out of bed, when your heart rate is at its lowest and most stable, ideally averaged over a few mornings for a more reliable number.