How this calculator works
Maximum heart rate is first estimated from age. The anaerobic threshold is then placed in a band at 80 to 90 percent of that maximum, a common coaching range for the intensity where lactate begins to rise. The three maximum heart rate formulas differ by a few beats per minute, which shifts the band by a similar amount. The band is a training guide, not a measurement: two people the same age can have thresholds many beats apart, and the true value is best found with a field test or a lactate test.
Formula
Haskell and Fox: 220 - age. Nes: 211 - 0.64 x age. Tanaka, Monahan and Seals: 208 - 0.7 x age. Threshold band = maximum heart rate x the lower and upper percentages.
Worked example
A 30-year-old using the Tanaka formula has an estimated maximum of 208 - 21 = 187 bpm. At 80 to 90 percent, the anaerobic threshold band is 150 to 168 bpm. The Haskell formula gives 190 bpm and shifts the band to 152 to 171; the Nes formula gives 191.8 and shifts it to 153 to 173.
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Frequently asked questions
What is anaerobic threshold?
It is the exercise intensity at which blood lactate begins to accumulate faster than it can be cleared. Athletes can hold work near that intensity for a limited time, and training just below it improves endurance.
Why is the band 80 to 90 percent?
Many trained endurance athletes reach threshold in that part of the maximum heart rate range, but the spread is wide. The adjustable percentages let you use a narrower band if you have tested your own threshold.
Can I train by this estimate alone?
Use it as a starting point for easy aerobic work and tempo sessions. If a field test, a power meter or lab data is available, use that instead, and treat symptoms, pace and RPE as more important than a formula.