Is 220 minus age an accurate formula for max heart rate?

The 220 minus age formula is a rough estimate accurate to within about 10 to 15 bpm for most adults. It systematically overestimates HRmax for younger adults and underestimates it for older adults. The Tanaka formula (211 minus 0.64 times age) is significantly more accurate, especially for adults over 40. The Gellish formula (191.5 minus 0.007 times age squared) is the most accurate for older athletes. For training prescription, any of these is close enough; for race-day pacing, a measured HRmax from a field test or VO2 max lab test is more reliable.

What heart rate zone should I train in?

A well-rounded training plan distributes time across zones. The polarized model used by most successful endurance athletes is roughly 80 percent of training time in Zone 1-2 (easy aerobic) and 20 percent in Zone 4-5 (threshold and VO2 max), with very little time in Zone 3. The reason: easy training builds aerobic base without accumulating fatigue, and hard training drives the fitness adaptations. Spending too much time in Zone 3 produces moderate fatigue without strong adaptation in either direction.

How do I find my resting heart rate?

Measure your resting heart rate first thing in the morning, before getting out of bed and before drinking caffeine. Take 60 seconds of pulse readings at the wrist or neck, count the beats, and that is your resting HR. For more reliable data, measure over a week and average the seven readings. A smartwatch records resting HR automatically. Typical resting HR is 60 to 80 bpm for adults; trained endurance athletes often have resting HR in the 40s or even high 30s.

Why is the Karvonen formula better than percent of HRmax?

The Karvonen formula uses heart rate reserve, defined as HRmax minus resting HR, then applies the target percentage to that reserve and adds resting HR back. The result accounts for individual fitness: two athletes with the same HRmax but very different resting HR will get different zone targets, which matches how the body actually responds. The percent of HRmax method ignores resting HR and treats all athletes the same, which is fine for casual fitness but less accurate for serious training. Karvonen is the default in serious training plans for this reason.

Can a smartwatch find my heart rate zones automatically?

Most smartwatches estimate HRmax from age and adjust based on detected workout intensities, then compute zones from there. The result is close but not great: the watch usually overestimates HRmax for fit users (because they hit higher HRmax than the age formula predicts) and rarely accounts for resting HR. For serious training, override the watch with a measured HRmax (from a stress test or maximal effort run) and a measured resting HR. Use the Karvonen method in the watch settings if it is available, percent of HRmax otherwise.

Tools · Heart rate zones calculator

Heart rate zones calculator: bpm ranges for each training zone.

Updated 2026-05-21 · 7 min read

Enter your age. Optionally enter your resting heart rate (enables the more accurate Karvonen method) and your measured HRmax if you know it. The calculator returns the bpm range for all five training zones, along with a brief description of what each zone is for.

Training zones

Zone	Name	% HRmax	bpm range	Used for

What heart rate zones are

A heart rate zone is a range of beats per minute that corresponds to a specific training intensity. The zones go from very easy (Zone 1) to maximum (Zone 5). Each zone trains a different physiological adaptation: Zone 2 builds aerobic base, Zone 4 raises lactate threshold, Zone 5 improves VO2 max. Knowing your zone bpm ranges lets you train at the intensity a workout actually calls for, instead of guessing.

How to find your true HRmax

The most accurate way is a graded exercise test in a lab, which costs USD 100 to 300. The next best is a field test: warm up for 15 minutes, then run a 1.5-mile time trial as hard as you can sustain. The peak heart rate during the last 30 seconds, plus 5 bpm, is a reasonable estimate of HRmax. The 220-age formula is the worst option but the most convenient. A smartwatch's auto-detected HRmax is somewhere in between and usually underestimates by 5 to 10 bpm in trained athletes.

Karvonen vs. % HRmax method

The percent of HRmax method multiplies your maximum heart rate by a target percentage. Simple and convenient. The Karvonen method first subtracts your resting heart rate from HRmax to get heart rate reserve, then applies the percentage to that reserve, then adds resting HR back. The result personalizes the zones to your actual fitness: a fitter athlete with a low resting HR gets lower zone bpm targets than a less fit one with the same age. For serious training, Karvonen is the standard.

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