VO2max from Resting Heart Rate Calculator

How it is calculated

The estimate depends only on the ratio of maximum to resting heart rate: VO2max = 15.3 × HRmax ÷ HRrest, in mL of oxygen per kg of body weight per minute. Heart rates are in beats per minute. If you leave maximum heart rate empty or at 0, the tool uses 220 − age. It also shows METs (VO2max ÷ 3.5) and heart-rate reserve (HRmax − HRrest). If you enter a body weight in kg, it adds absolute capacity in L/min: VO2max × weight ÷ 1000; without weight that line shows a dash. Inputs outside these limits give no result: age above 0 up to 120, resting rate 25 to 130 bpm, maximum rate at most 250 and above the resting rate, weight 2 to 650 kg. It is a rough fitness estimate, not a lab measurement.

Common mistakes

• Measuring resting heart rate after getting out of bed, a coffee or a stressful moment. Because resting rate is in the denominator, a few extra beats noticeably lower the result.
• Entering a maximum from a hard workout when you did not really go all-out. That understates HRmax: 180 instead of 190 bpm lowers the estimate from 48.5 to 45.9.
• Comparing the number with a lab or treadmill VO2max. This is a two-pulse estimate and can be off by a lot for any one person.
• Reading the L/min line as relative fitness. It scales with body weight, so a heavier person gets a larger absolute value from the same mL/kg/min.
• Entering weight in pounds. The weight field is in kg, so 154 lb typed as 154 shows 7.46 L/min instead of 3.39, while the mL/kg/min figure does not change.