Karvonen Method (Heart Rate Reserve)

The Karvonen formula uses heart rate reserve (HRmax − HRrest) to set training intensities. More personalised than percentage of HRmax because it accounts for your resting heart rate.

The Karvonen Formula, Worked Through

The Karvonen formula uses heart rate reserve (HRR), the difference between your maximum and resting heart rate. Two athletes with the same HRmax but different resting rates end up with very different training targets — which is why %HRR is generally preferred over %HRmax for anyone who has measured their resting HR.

Target HR = HRrest + (Intensity% × (HRmax − HRrest))

Worked example: two 40-year-olds, same HRmax, different Zone 2

Athlete	HRmax	HRrest	HRR	Zone 2 (60–70% HRR)	Zone 2 (60–70% HRmax)
Trained runner	180	45	135	126–140 bpm	108–126 bpm
Untrained office worker	180	75	105	138–149 bpm	108–126 bpm

Notice that %HRmax gives both athletes the same target (108–126 bpm) — clearly too low for the untrained athlete, whose easy pace already puts them at 130+ bpm. Karvonen fixes this by anchoring the range to each athlete's actual HR reserve.

Where the formula came from

Martti Karvonen and colleagues at the University of Helsinki published the method in 1957 after studying young men on a stationary bike. They observed that the linear relationship between HR and oxygen uptake held far better when expressed as a fraction of HRR than as a fraction of HRmax alone.

Reference: Karvonen MJ, Kentala E, Mustala O. The effects of training on heart rate: a longitudinal study. Annales Medicinae Experimentalis et Biologiae Fenniae. 1957;35(3):307–15.

When Karvonen breaks down

Inaccurate resting HR — measure on 3+ mornings before you stand up, then average. A single reading after coffee or a poor night's sleep is worthless.
Beta-blockers compress the reserve; formula-derived targets no longer correspond to metabolic zones.
Detrained state — after a long layoff HRrest rises and HRmax may drop; recalculate after 4–6 weeks of consistent training.

Heart Rate Zones (reference: age 30, HRmax ≈ 187 bpm, Tanaka)

Zone	Name	% HRmax	BPM (age 30)	Primary use
1	Recovery	50–60%	94–112	Warm-up, recovery, active rest
2	Endurance	60–70%	112–131	Aerobic base, fat oxidation
3	Aerobic	70–80%	131–150	Tempo, aerobic capacity
4	Threshold	80–90%	150–168	Lactate threshold intervals
5	Maximum	90–100%	168–187	VO₂ max, neuromuscular power

Maximum Heart Rate Formulas

Tanaka (2001) — our default for men: HRmax = 208 − 0.7 × age. Meta-analysis of 18,712 participants.
Gulati (2010) — our default for women: HRmax = 206 − 0.88 × age. Developed on 5,437 women.
Gellish (2007): HRmax = 207 − 0.7 × age. Developed on regularly active adults.
Nes / HUNT (2013): HRmax = 211 − 0.64 × age. Norwegian HUNT Fitness Study on 3,320 healthy adults.
Fox (1971) — historical reference: HRmax = 220 − age. Simple and widely quoted, but a 1970s approximation with ±10–12 bpm variability that overestimates for active adults.

No formula is universally “correct.” The only way to know your true HRmax is a supervised maximum-effort test.

Disclaimer: This calculator is for informational purposes only and does not provide medical advice. Always consult with a healthcare professional before starting any new exercise program.

Explore all guides

SnapHRZones — Heart Rate Zone Calculator · Guides · FAQ · About

This page requires JavaScript for the interactive calculator. Enable JavaScript for personalised results.