Calculate your estimated VO2max from a running effort of 1,500 metres or longer using the Daniels-Gilbert oxygen-cost equations, rank your result against lab-tested adults in the FRIEND registry (Kaminsky et al., 2015), and turn it into a fitness age using the FRIEND age-decade medians, an idea developed in the HUNT study (Nes et al., 2011).
Core Equation & Guard-Rail
VO₂(v) = −4.6 + 0.182258v + 0.000104v² · %VO₂max(t) = 0.8 + 0.1894e^(−0.0128t) + 0.2990e^(−0.1933t)
Requires a hard running effort of at least 1,500 metres and 3 minutes. Lab cardiopulmonary exercise testing (CPET) remains the clinical reference; a field estimate can sit several points either side of it. Fitness age and percentile are for motivation, not a medical assessment.
44.5 mL/kg
Daniels-Gilbert VDOT
58th %ile
FRIEND Registry Cohort
31 yrs
3 yrs younger than your age
| Daniels Training Zone | Target Pace (/km) | Physiological Purpose |
|---|---|---|
| Easy / Zone 2 | 5:22 - 5:57/km | Aerobic base, capillary density & mitochondrial volume |
| Marathon Pace | 4:57 - 5:09/km | Specific aerobic durability & glycogen economy |
| Lactate Threshold (T) | 4:40 - 4:48/km | Raise lactate clearance ceiling (20 to 40 min efforts) |
| VO2max Interval (I) | 4:13 - 4:21/km | Maximal oxygen uptake (3 to 5 min repeats) |
| Repetition (R) | 3:54 - 4:03/km | Running economy & neuromuscular speed (200m to 400m) |
A field estimate for motivation, not a medical assessment. Lab testing is the clinical reference.
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VO₂(v) = −4.6 + 0.182258v + 0.000104v² · %VO₂max(t) = 0.8 + 0.1894e^(−0.0128t) + 0.2990e^(−0.1933t)
Requires a hard running effort of at least 1,500 metres and 3 minutes. Lab cardiopulmonary exercise testing (CPET) remains the clinical reference; a field estimate can sit several points either side of it. Fitness age and percentile are for motivation, not a medical assessment.
General fitness and training estimates only, labelled EST. Not medical advice or a clinical diagnosis.
Verified Literature
Your VO2max estimate from a hard run comes straight from Daniels' VDOT tables, the pace-to-fitness model coaches have trusted for over forty years.
Daniels, J. Daniels' Running Formula, 4th edition. Champaign, IL: Human Kinetics, 2021. ISBN 9781718203662, 320 pp. Carries forward the VDOT tables and the velocity-to-oxygen-cost regressions first published in Daniels, J. & Gilbert, J. Oxygen Power: Performance Tables for Distance Runners, Tempe, AZ, 1979.
View the sourceThe "fitter than X% of people your age" line is read off real reference standards built from thousands of lab-tested adults, so your percentile actually means something.
Kaminsky, L.A., Arena, R. & Myers, J. "Reference Standards for Cardiorespiratory Fitness Measured With Cardiopulmonary Exercise Testing: Data From the Fitness Registry and the Importance of Exercise National Database." Mayo Clinic Proceedings, 2015;90(11):1515-1523. doi:10.1016/j.mayocp.2015.07.026
View the sourceFitness age is the idea that your VO2max can sit younger or older than your birthday suggests, first mapped across 4,637 adults in Norway's HUNT study.
Nes, B.M., Janszky, I., Vatten, L.J., Nilsen, T.I.L., Aspenes, S.T. & Wisløff, U. "Estimating VO2peak from a nonexercise prediction model: the HUNT Study, Norway." Medicine & Science in Sports & Exercise, 2011;43(11):2024-2030. doi:10.1249/MSS.0b013e31821d3f6f
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We convert your distance and finish time into velocity in metres per minute, calculate the oxygen cost of running at that speed, and divide by the fraction of VO2max sustainable for that duration using the Daniels and Gilbert (1979) equations.
The Fitness Registry and the Importance of Exercise National Database (Kaminsky et al., Mayo Clinic Proceedings 2015) compiled cardiopulmonary exercise tests from thousands of healthy men and women across age decades 20s through 70s.
Fitness age is the idea, developed in Norway’s HUNT study (Nes et al., 2011), that your VO2max can sit younger or older than your birthday suggests. Here it is the age whose typical (median) VO2max in the FRIEND reference data matches yours, so a 42-year-old with the median VO2max of a 30-year-old has a fitness age of 30. It is a motivating estimate from a field run, not a health measurement.