Target Heart Rate Calculator
The Karvonen method improves on simple age-based formulas by incorporating your resting heart rate, producing a personalized target that reflects your current cardiovascular fitness level. This calculator gives your target heart rate at any exercise intensity percentage.
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Formula
THR = (HRmax − HRrest) × Intensity% + HRrest; HRmax = 220 − Age
Heart rate reserve (HRR) is the difference between your maximum heart rate (220 minus age) and your resting heart rate. The Karvonen method sets your target as a fraction of HRR added back to resting HR. This accounts for individual fitness: a fitter person with a lower resting HR will have a different absolute target than a sedentary person even at the same percentage.
How to use the Target Heart Rate Calculator
- 1
Enter your age
Value should be in years.
- 2
Enter your resting heart rate
Value should be in bpm.
- 3
Enter your exercise intensity
Value should be in %.
- 4
Read your results instantly
Results update in real time as you type.
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Heart rate training zones
Different exercise intensities produce different physiological adaptations. At 50–60% of heart rate reserve, you are in the fat-burning zone — low intensity, sustainable for long durations, primarily using fat as fuel. At 70–80%, you are in the aerobic or cardio zone, improving cardiovascular efficiency and endurance. At 80–90%, you cross into the anaerobic threshold, building speed and power but only sustainable for shorter periods. At 90–100%, you are at near-maximal effort — interval training territory. Most general fitness goals are achieved in the 65–80% zone.
Measuring resting heart rate accurately
Your resting heart rate (RHR) is best measured first thing in the morning, before getting out of bed, after at least 5 minutes of lying still. Normal RHR for adults is 60–100 bpm, though fit athletes often have RHRs in the 40–60 range. A lower RHR generally reflects better cardiovascular fitness. Measure for 3 consecutive mornings and average the readings for the most accurate input value. A heart rate monitor or wearable device makes this trivial, but even a manual count of 30 seconds × 2 works well.
Tips & Insights
Check your heart rate mid-workout
Pause briefly during exercise to take a 10-second pulse count and multiply by 6, or use a chest strap heart rate monitor for continuous real-time data.
Start conservatively
If you are new to exercise or returning after a break, target the 50–65% intensity range. Build progressively over 4–6 weeks before moving into higher zones.
The 220-minus-age formula has variability
Individual max heart rates can vary ±10–20 bpm from the 220-age estimate. A graded exercise stress test with medical supervision gives the most accurate HRmax measurement.
Worked Examples
30-year-old, 65 bpm rest, 70% intensity
Target HR ≈ 151 bpm; Max HR: 190 bpm
45-year-old, 58 bpm rest, 80% intensity
Target HR ≈ 157 bpm; Max HR: 175 bpm
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Frequently Asked Questions
What is a good resting heart rate?
For most adults, 60–100 bpm is normal. Athletes often have resting heart rates of 40–60 bpm due to improved cardiac efficiency from regular training.
Should I exercise at my target heart rate the whole time?
Not necessarily. Warm up and cool down at lower intensities. Aim to spend the majority of your main workout within your target zone.
Can medications affect my heart rate targets?
Yes. Beta-blockers significantly lower maximum heart rate and should not be combined with standard heart rate formulas. Ask your doctor for modified targets.
Is a chest strap or wrist monitor more accurate?
Chest straps are consistently more accurate than wrist-based optical monitors, especially during high-intensity exercise where wrist movement causes reading errors.
How does fitness affect my target heart rate?
As you get fitter, your resting heart rate decreases. A lower RHR expands your heart rate reserve, meaning you have a wider working range between rest and maximum.
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