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Karvonen Formula Calculator

Target heart rate from heart rate reserve: THR = ((HRmax − HRrest) × intensity%) + HRrest. Pick the classic 220 − age, the research-backed Tanaka (208 − 0.7 × age), or your own measured max HR — then slide the intensity to get your exact training target plus a full 5-zone table.

Educational tool, not medical advice. These numbers are estimates for healthy adults and do not diagnose or treat any condition. Consult a physician before starting or changing a training program, especially with a heart condition, high blood pressure, or medication affecting heart rate.

1. Your numbers

ACSM-style moderate-to-vigorous range: 50–85% of HRR. Zones below cover 50–100%.

What is the Karvonen formula?

The Karvonen formula was published in 1957 by Finnish physiologist Martti Karvonen and colleagues (“The effects of training on heart rate”, Annales Medicinae Experimentalis et Biologiae Fenniae). Instead of a plain percentage of max HR, it works from your heart rate reserve (HRR) — the gap between your max and resting heart rate — so two people of the same age but different fitness levels get different, personal targets.

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

Worked example (verified): a 35-year-old with resting HR 65 bpm, using 220 − 35 = 185 bpm max HR. HRR = 185 − 65 = 120 bpm. At 70% intensity: (120 × 0.70) + 65 = 149 bpm. With the Tanaka estimate (208 − 0.7 × 35 = 183.5), the same 70% gives 148 bpm — try both above and compare.

The classic 220 − age estimate was never formally validated; the Tanaka equation (208 − 0.7 × age) comes from a 2001 meta-analysis of 18,712 subjects (Tanaka, Monahan & Seals, J Am Coll Cardiol) and predicts max HR better, especially past age 50.

How to measure resting heart rate

  1. Measure first thing in the morning, before getting out of bed.
  2. Lie still for a few minutes, then count your pulse for a full 60 seconds (or read a chest strap).
  3. Repeat on 3 mornings and use the average.
  4. Avoid caffeine, alcohol, and hard training the evening before — they inflate the reading.

Karvonen training zones explained

  • Zone 1 — Recovery (50–60% HRR): easy warm-ups, cool-downs, active recovery days.
  • Zone 2 — Aerobic base (60–70% HRR): fat-burning, builds endurance; you can hold a conversation.
  • Zone 3 — Aerobic (70–80% HRR): tempo pace; raises lactate threshold.
  • Zone 4 — Threshold (80–90% HRR): hard intervals; biggest VO2max gains.
  • Zone 5 — Maximum (90–100% HRR): sprint intervals; short bursts with full recovery only.

Related: for a full multi-method zone lab (Karvonen, % of max, LTHR, Friel, Maffetone side by side with sport presets), see our heart rate zone lab. This page stays focused on the Karvonen formula itself — one intensity in, one exact target out. Also see heart bpm calculator.

Frequently asked questions

What is the Karvonen formula?
The Karvonen formula, published by Finnish physiologist Martti Karvonen and colleagues in 1957, calculates target heart rate from heart rate reserve (HRR): Target HR = ((HRmax − HRrest) × intensity%) + HRrest. It personalizes training zones with your resting heart rate, unlike a plain percentage of max HR.
How do I use the Karvonen formula calculator?
Enter your age and a properly measured resting heart rate, pick a max-HR estimator (220 minus age, Tanaka 208 − 0.7 × age, or your own measured max HR), then set the intensity with the slider. The calculator shows your heart rate reserve, the target heart rate at that intensity, the worked steps, and a full 5-zone table.
What is heart rate reserve (HRR)?
Heart rate reserve is HRmax minus resting HR — the usable range your heart has to work with. A trained person with a low resting HR has a larger reserve than a sedentary person of the same age and max HR, so the Karvonen formula gives them different, more accurate training targets.
Should I use 220 minus age or the Tanaka formula for max heart rate?
220 minus age is the classic rough estimate, but it was never formally validated and underestimates max HR in older adults. The Tanaka equation (208 − 0.7 × age) comes from a 2001 meta-analysis of 18,712 subjects and fits better, especially above age 50. A directly measured peak HR from a recent maximal effort is more accurate than either estimate.
How do I measure my resting heart rate correctly?
Measure first thing in the morning before getting out of bed: lie still for a few minutes, then count your pulse for 60 seconds (or use a chest strap). Repeat on 3 mornings and use the average. Avoid caffeine, hard training, and stress the evening before, since all of these raise the reading.
What are the Karvonen heart rate training zones?
Zone 1 Recovery (50–60% of HRR): warm-up and cool-down. Zone 2 Aerobic base (60–70%): fat burning and endurance, conversational pace. Zone 3 Aerobic (70–80%): tempo, improves lactate threshold. Zone 4 Threshold (80–90%): anaerobic intervals, VO2max. Zone 5 Maximum (90–100%): sprint intervals, short bursts only.
What intensity should a beginner start at?
Beginners should start at 50–60% of heart rate reserve (Zone 1–2) for the first weeks, then progress gradually toward 60–70%. The American College of Sports Medicine has long recommended the Karvonen method for exercise prescription because it scales with individual fitness. Stop and consult a professional if you feel dizzy, chest pain, or unusual shortness of breath.
Is the Karvonen method better than a simple percentage of max heart rate?
For most people, yes. A plain percentage of max HR gives the same zones to everyone of the same age, ignoring fitness. The Karvonen method anchors zones to your personal resting heart rate, so a fit and an unfit person of the same age get different targets — research links %HRR more closely to %VO2max than %HRmax does.
Can I use a measured max heart rate instead of a formula?
Yes — and you should if you have one. Select the “measured max HR” option and enter the highest reliable heart rate from a recent race, ramp test, or maximal effort with a chest strap. It is always more accurate than any age-based estimate, which carries roughly ±7–12 bpm of individual variation.
Is the Karvonen formula accurate and safe to use?
The Karvonen formula is a widely used coaching and exercise-prescription method, but it is an estimate: age-based max-HR formulas carry individual variation, and the numbers here are educational, not medical advice. Consult a physician before starting a new training program, especially if you have a heart condition, high blood pressure, or take medication that affects heart rate.

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