Most "target heart rate" calculators ask only your age and hand you a single number. The Karvonen method goes one important step further: it also uses your resting heart rate, the pulse your body runs at when it is fully relaxed. Because that number reflects how fit your heart actually is, the target you get back is personal rather than averaged across every person your age. This calculator walks through that method in seconds and gives you both a single training number at your chosen intensity and the full 50% to 85% heart-rate-reserve band.
The formula is simple and was developed by the Finnish physiologist Martti Karvonen in the 1950s. It says your Target Heart Rate (THR) equals your heart rate reserve multiplied by your desired exercise intensity, plus your resting heart rate. Plug in your age, your morning resting pulse, and how hard you want to train, and the result is the beats-per-minute you should aim for during cardio.
How to Use
- Measure your resting heart rate first. The most accurate reading is taken on the morning after a full night of sleep, before you sit up, drink coffee, or check your phone. Count your pulse at the wrist or neck for a full 60 seconds. Repeat on two or three mornings and average the values — this number drives the whole calculation.
- Enter your age. The engine estimates your maximum heart rate (HRmax) with the classic 220-minus-age rule. Note that this is a population estimate; newer formulas such as Tanaka may be slightly more accurate, but 220 minus age remains the standard taught by the American Heart Association.
- Type your resting heart rate into the second field. A value between 40 and 60 bpm is typical for a trained endurance athlete, 60 to 70 for a reasonably active adult, and above 70 may suggest room for improvement.
- Set your exercise intensity. The default is 70% of heart rate reserve, which is a solid aerobic effort. Slide it down toward 50% for warm-ups, recovery walks, or beginner sessions, and up toward 85% for harder intervals.
- Read the result card. You will see your estimated maximum heart rate, your heart rate reserve, the target heart rate at your chosen intensity, and the low and high edges of the 50% to 85% training band. Wear a chest strap or wrist monitor during your next run, ride, or row, and try to hold the middle of that band for the bulk of the workout.
The Karvonen Formula
The math behind the calculator is:
THR = ((HRmax − HRrest) × intensity%) + HRrest
where HRmax = 220 − age.
Worked example for a 30-year-old with a resting heart rate of 60 bpm who wants to train at 70%:
- HRmax = 220 − 30 = 190 bpm
- Heart rate reserve = 190 − 60 = 130 bpm
- THR = (130 × 0.70) + 60 = 91 + 60 = 151 bpm
That 151 is the number to aim for. Compare it with the simple age-only method, which would suggest roughly 142 bpm for the same person — the difference matters, especially as your fitness improves and your resting pulse drops. A fitter version of the same 30-year-old with a resting heart rate of 45 bpm has a larger reserve (145 bpm) and a 70% target of 146 bpm, so the personalized number rises rather than staying frozen at the age-only estimate.
The 50% to 85% range is the conventional Karvonen training band: 50% is the lower edge of moderate activity, and 85% sits near the top of vigorous, near-threshold effort. Beyond 85% most people drift into anaerobic territory where form collapses quickly.
Why Resting Heart Rate Matters
Your resting heart rate is one of the simplest markers of cardiovascular fitness available. Each heartbeat moves a volume of blood; a stronger heart simply needs fewer beats per minute at rest. Runners, cyclists, and triathletes often rest in the high 40s or low 50s, while adults who are new to exercise may see 70 to 80 bpm.
Because the Karvonen method bakes that number into the formula, your target naturally rises as you get fitter. A 40-year-old with a resting heart rate of 75 bpm has a 70% target of about 139 bpm. After several months of consistent training, if that resting pulse falls to 60 bpm, the same 70% target climbs to roughly 145 bpm — meaning the same effort now carries more oxygen and more speed. That feedback loop is why coaches prefer Karvonen over a static age-based table.
Examples
Example 1 — A beginner starting walking. A 45-year-old woman measures a resting heart rate of 72 bpm and wants a gentle, talkable workout. HRmax is 175, reserve is 103, and at 50% intensity her target heart rate is 124 bpm. A brisk neighborhood walk that lifts her pulse to around 120 to 130 is exactly the right zone to build an aerobic base without joint stress.
Example 2 — A runner doing tempo intervals. A 28-year-old male runner with a resting heart rate of 48 bpm sets intensity to 85%. HRmax is 192, reserve is 144, and his target is 170 bpm. During interval sessions he should expect to hold roughly 165 to 175 bpm on the hard repetitions and let the heart rate fall back toward 130 bpm during the recoveries.
Example 3 — A busy professional at the default setting. A 35-year-old enters age 35, resting heart rate 65, and leaves intensity at the default 70%. HRmax is 185, reserve is 120, and the target heart rate is 149 bpm, with a training band from 125 bpm (50%) to 167 bpm (85%). A lunchtime jog, a spin class, or a weekend bike ride that keeps him between 130 and 165 is productive.
FAQ
What is the Karvonen method?
The Karvonen method is a heart-rate-based training prescription developed by Finnish researcher Martti Karvonen. Instead of using only age to set intensity, it uses your heart rate reserve — the gap between your maximum and resting heart rate — so the target reflects your current fitness rather than a generic age average.
How is target heart rate calculated with Karvonen?
First estimate maximum heart rate as 220 minus your age. Subtract your resting heart rate to get heart rate reserve. Multiply that reserve by your desired intensity percentage, then add your resting heart rate back. The result, in beats per minute, is the target heart rate for that effort.
What is a good resting heart rate?
For most adults, a resting heart rate between 60 and 70 bpm is typical. Trained endurance athletes often sit between 40 and 50 bpm. A sustained resting pulse above 80 bpm, especially when paired with other symptoms, is worth discussing with a doctor.
What do 50%, 70%, and 85% mean in training?
At 50% of heart rate reserve you are in a light, recovery-effort zone suitable for warm-ups and beginners. At 70% you are in the aerobic zone — the sweet spot where most endurance fitness is built. At 85% you are near your anaerobic threshold, suitable for intervals but not for long continuous sessions.
Is the 220-minus-age formula accurate?
It is a widely taught population estimate, not a precise individual measurement. Real maximum heart rate varies by as much as 10 to 15 bpm around the predicted value. If you want a true number, a supervised maximal stress test or a hard all-out interval session is the only way to find it; otherwise, use the formula as a starting point and adjust by how the effort feels.
Can I use this calculator while taking heart-rate-affecting medication?
Medications such as beta-blockers deliberately lower both resting and maximum heart rate, which makes the 220-minus-age rule unreliable. If you take heart medication, rely on perceived exertion and your doctor's or cardiologist's guidance rather than the numbers produced here.
Disclaimer
This Karvonen calculator is provided for informational purposes only and is not medical advice. Target heart rate estimates are population approximations based on the 220-minus-age formula and may not reflect your true maximum heart rate, especially if you are pregnant, older than 60, taking heart-rate-affecting medication, or managing a known cardiovascular condition. Stop exercising and seek immediate medical attention if you experience chest pain, dizziness, abnormal shortness of breath, or an irregular heartbeat. Consult a qualified physician, cardiologist, or certified exercise professional before starting or increasing any vigorous exercise program.