Find your target heart rate for training using the Karvonen (Heart Rate Reserve) method and the percentage of max HR method. Includes five training zones.
| Quantity | Value | Formula | Notes |
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| Zone | % of HRR | % of max HR | Heart rate range | Training benefit |
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| Zone | Karvonen (HRR) | % of max HR | Difference |
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| Intensity | % of HRR | Feels like | Your status |
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| Metric | Value | Notes |
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Karvonen, M.J., Kentala, E., Mustala, O. "The effects of training on heart rate: a longitudinal study." Annales Medicinae Experimentalis et Biologiae Fenniae, 1957. (Original Heart Rate Reserve method: HRtarget = (HRmax − HRrest) × %intensity + HRrest.)
Tanaka, H., Monahan, K.D., Seals, D.R. "Age-predicted maximal heart rate revisited." Journal of the American College of Cardiology, 2001. (208 − 0.7 × age; more accurate than 220 − age across all adult ages.)
Fox, I.S., Haskell, W.L. "Physical activity and the prevention of coronary heart disease." Annals of Clinical Research, 1971. (Original 220 − age formula; standard error of estimate ±12 bpm.)
Gulati, M., Shaw, L.J., Thisted, R.A., Black, H.R., Bairey Merz, C.N., Arnsdorf, M.F. "Heart rate response to exercise stress testing in asymptomatic women." Circulation, 2010. (206 − 0.88 × age; validated in 5,437 asymptomatic women.)
Nes, B.M., Janszky, I., Wisløff, U., Støylen, A., Karlsen, T. "Age-predicted maximal heart rate in healthy subjects: The HUNT Fitness Study." Heart, 2013. (211 − 0.64 × age; large Norwegian cohort of 3,320 healthy adults.)
American College of Sports Medicine. "ACSM's Guidelines for Exercise Testing and Prescription," 11th ed., 2021. (%HRR is the recommended method for individualised exercise prescription.)
Polar Electro. "Running heart rate zones: the basics." 2024. (Standard five-zone boundaries: 50 to 60, 60 to 70, 70 to 80, 80 to 90, 90 to 100 percent of max HR.)
Cleveland Clinic. "Exercise heart rate zones explained." 2022. (Zone-by-zone benefits and the talk-test method for self-regulation.)
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Target heart rate is the beats-per-minute range your heart should reach during exercise to train at a chosen intensity. It’s expressed either as a percentage of your maximum heart rate or as a percentage of your heart rate reserve, the gap between your resting and max heart rate. The American College of Sports Medicine recommends 50–85% of heart rate reserve for aerobic training in healthy adults, with 40–50% as a starting point for people with low fitness. That range is the foundation for the zones this calculator produces.
The concept comes from the Karvonen method, published in 1957 by a Finnish physiologist who found that training intensity scales more accurately when you anchor it to the working range of your heart rather than to your maximum alone. Heart rate reserve is calculated as max HR minus resting HR. A person with a max HR of 187 bpm and a resting HR of 65 bpm has an HRR of 122 bpm. At 70% intensity, the Karvonen formula gives a target of 150 bpm. The percentage-of-max method ignores resting HR and gives 131 bpm at the same intensity. That 19 bpm gap is why the two methods produce different zones.
To calculate target heart rate with Karvonen, subtract your resting heart rate from your max heart rate to get heart rate reserve. Multiply HRR by your desired intensity as a decimal, then add your resting heart rate back. A 40-year-old with a resting HR of 62 bpm and a max HR of 180 bpm has an HRR of 118 bpm. At 75% intensity, the target is (118 × 0.75) + 62 = 151 bpm. Here’s how to run it in the calculator.
Enter your age. This drives the max HR formula. The default is 30 years.
Select your sex. This affects which max HR formula is auto-selected. Female switches to Gulati; male switches to Tanaka.
Enter your resting heart rate. The default is 65 bpm. Measure yours first thing in the morning before getting out of bed.
Choose a max HR formula. Tanaka is the default. Fox, Gulati, and Nes are alternatives. Custom lets you enter a lab-measured value.
Pick a calculation method. Karvonen uses heart rate reserve. Percentage of max HR uses a straight share of your maximum.
Set your intensity. The default is 70%. You can type a number or use the quick zone dropdown.
Read the hero panel. It shows your target heart rate in bpm, plus your resting HR, max HR, and intensity as context.
Check the five tables. The breakdown table shows every step. The zones table shows all five ranges. The comparison table shows Karvonen vs percentage side by side.
The calculator runs two formulas. The Karvonen formula is THR = (HRR × intensity) + RHR, where HRR = max HR − resting HR. The percentage-of-max formula is THR = max HR × intensity. Both produce a target in bpm. The Karvonen method adds your resting heart rate back into the result, which is why it produces a higher target at the same intensity when your resting HR is above zero.
Formula: THR (Karvonen) = ((Max HR − Resting HR) × Intensity%) + Resting HR
Formula: THR (Percentage) = Max HR × Intensity%
Formula: % of Max HR = (THR ÷ Max HR) × 100
Max HR itself comes from one of four published formulas. Fox: 220 − age. Tanaka: 208 − 0.7 × age. Gulati: 206 − 0.88 × age. Nes: 211 − 0.64 × age. Tanaka was developed from a meta-analysis of 351 studies covering 18,712 subjects and shows the lowest mean absolute error in a recent validation study. The Gulati formula was derived specifically from a cohort of 5,437 women and typically produces a lower max HR for women than the male-derived Fox formula.
A 42-year-old male cyclist has a resting heart rate of 54 bpm. He’s using the Tanaka formula. His max HR is 208 − (0.7 × 42) = 208 − 29.4 = 178.6, rounded to 179 bpm. His heart rate reserve is 179 − 54 = 125 bpm. He wants to train at 80% intensity Zone 4, threshold work.
Step 1: HRR = 179 − 54 = 125 bpm.
Step 2: Karvonen target = (125 × 0.80) + 54 = 100 + 54 = 154 bpm.
Step 3: Percentage-of-max target = 179 × 0.80 = 143 bpm.
The two methods differ by 11 bpm at the same intensity. The Karvonen result is higher because it adds resting HR back. The calculator places 80% intensity in Zone 4 (Threshold) and shows that 154 bpm is 86% of his max HR. The intensity table marks this as “Hard” breathing heavily, no talking. If he dropped to 70% intensity, his Karvonen target would be 142 bpm and he’d be in Zone 3 (Tempo). The difference between Zone 3 and Zone 4 is 12 bpm on his chart.
Four variables change your target heart rate: max HR, resting HR, intensity, and which formula you choose. Max HR sets the ceiling. Resting HR sets the floor. Intensity picks the point between them. Formula choice shifts the ceiling up or down by 5–15 bpm depending on your age and sex.
Age: Max HR declines roughly 0.6–0.9 bpm per year depending on the formula. A 30-year-old and a 60-year-old have max HR estimates that differ by 20–30 bpm.
Resting heart rate: A lower resting HR widens your heart rate reserve and pushes Karvonen targets higher at the same intensity. Trained athletes often have resting HRs in the 40s.
Sex: The Gulati formula produces a lower max HR for women than the male-derived Fox formula. The calculator auto-switches to Gulati when you select female.
Intensity: Every 5% increase in intensity adds roughly 6–8 bpm to your target, depending on your HRR.
Max HR formula: Tanaka and Nes give similar results for young adults but diverge at older ages. Fox underestimates max HR in older adults.
Medications: Beta blockers lower both resting and max HR. The calculator cannot adjust for medication, so targets may be too high for people on rate-controlling drugs.
Measurement error in resting HR: A resting HR taken after coffee or a stressful morning commute will be 5–10 bpm higher than a true morning reading.
Most target heart rate errors come from bad resting HR measurements or using the wrong formula for your situation. The fixes are simple. The tips below come from common failure modes in exercise testing and prescription.
Measure resting HR before getting out of bed. Mayo Clinic recommends taking your pulse first thing in the morning. Count beats for 30 seconds and multiply by two.
Don’t use your watch’s resting HR without checking it. Wearable devices can be off by 5–10 bpm. A manual morning count is more reliable.
Use Tanaka unless you have a reason not to. It has the best accuracy across the widest age range. Switch to Gulati if you’re female and want a women-specific estimate.
Switch to Custom if you’ve done a max HR test. A lab-measured or race-measured max HR beats any formula.
Check the comparison table before you commit. The Karvonen vs percentage table shows the gap between methods for your numbers. If the gap is under 5 bpm, either method works.
Round to the nearest whole bpm. The calculator does this automatically. Don’t try to hold a target like 147.3 bpm.
Recheck your zones every six months. Resting HR changes with fitness. Zones that were accurate in January may be off by 5 bpm by July.
A good target heart rate is one that falls within the zone matching your training goal. For moderate aerobic work, 60–70% of heart rate reserve is a common range. For threshold training, 80–90% HRR. The calculator marks your current intensity on the zones table.
Use the Karvonen formula: subtract your resting heart rate from your max heart rate, multiply by intensity, then add resting heart rate back. A 35-year-old with a max HR of 184 and resting HR of 60 at 70% intensity gets ((184 − 60) × 0.70) + 60 = 147 bpm.
The Karvonen formula calculates target heart rate using heart rate reserve. It is THR = ((Max HR − Resting HR) × Intensity%) + Resting HR. It was published by Karvonen, Kentala, and Mustala in 1957 and is the ACSM-preferred method for individualised exercise prescription.
Karvonen is more accurate because it accounts for resting heart rate and adapts to your fitness level. Percentage of max HR is simpler but ignores resting HR entirely. The ACSM recommends %HRR over %max HR for exercise prescription.
A normal resting heart rate for adults is 60–100 bpm, according to Mayo Clinic. Trained athletes often have resting rates in the 40s. A resting HR consistently above 100 bpm warrants a conversation with a healthcare provider.
The 220 − age formula has a standard error of estimate of about ±12 bpm. It tends to overestimate max HR in older adults. The Tanaka formula (208 − 0.7 × age) is more accurate across all ages and is the default in this calculator.
Heart rate reserve is the difference between your maximum heart rate and your resting heart rate. It represents the working range of your heart. A person with a max HR of 185 and resting HR of 60 has an HRR of 125 bpm.
The Gulati formula (206 − 0.88 × age) was developed specifically from a cohort of 5,437 women and typically produces a lower max HR estimate for women than the male-derived Fox formula. The calculator auto-selects Gulati when you choose female.
Zone 2 is 60–70% of heart rate reserve. It’s the aerobic base-building zone. You can hold a conversation in full sentences. Most of your weekly training volume should sit here if you’re building endurance.
Measure it first thing in the morning before getting out of bed. Place two fingers on your wrist below the thumb, count beats for 30 seconds, and multiply by two. A 15-second count multiplied by four also works.
You can enter your numbers, but the results will likely overestimate your true target heart rate. Beta blockers lower both resting and max HR. Talk to your doctor about exercise intensity if you’re on rate-controlling medication.
Zone 4 is 80–90% of heart rate reserve hard effort, race pace, lactate threshold work. Zone 5 is 90–100% maximum effort, VO2 max intervals, sprint work. You can hold Zone 4 for minutes; Zone 5 is seconds at a time.
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