Health
Heart Rate Calculator
Last updated: May 31, 2026
Written by Blake Boege
A heart rate calculator is a fitness assessment tool that estimates an individual's maximum heart rate and outlines target heart rate zones for physical exercise. It utilizes mathematical models like the simple age-based formula or the Karvonen method, which incorporates resting pulse for a more personalized baseline. By calculating heart rate percentages, the tool classifies workout intensities into recovery, aerobic fat-burning, cardiovascular, and maximum anaerobic thresholds, enabling individuals to optimize their exercise programs and track cardiovascular health.
Calculate your estimated maximum heart rate and target exercise zones for aerobic activity, fat burning, and peak cardio performance using standard and Karvonen formulas.
Quick Answer
Calculate your target training heart rate zones for different exercise intensities. Enter your age and resting heart rate to view maximum and target heart rate ranges.
e.g. 35
Estimated max HR uses 220 − age. Karvonen adds resting heart rate to give a more individualized target.
Estimated max HR
185 bpm
Percent-of-max method
Estimates only. People with cardiac conditions, on rate-affecting medication (such as beta-blockers), pregnant, or with symptoms during exercise should ask a clinician before training to target zones.
Examples
Age 30, simple percent of max method
max ≈ 190 · moderate 95 to 133 · vigorous 133 to 162
Age 45, simple percent of max method
max ≈ 175 · moderate 88 to 123 · vigorous 123 to 149
Age 30, resting 60, Karvonen method
reserve 130 · moderate 125 to 151 · vigorous 151 to 171
How it works
The 5 heart rate training zones
Your maximum heart rate (220 minus your age) gets divided into five training zones, each with a different fitness benefit:
ZONE 1 — VERY LIGHT (50-60% of max HR): Recovery and warm-up zone. Easy to maintain conversation. Used for warm-ups, cool-downs, and recovery between hard workouts.
ZONE 2 — LIGHT / FAT BURNING (60-70% of max HR): Often called the 'fat burning zone' because the body uses a higher percentage of fat for fuel here. Sustainable for hours. Best for building aerobic base and endurance.
ZONE 3 — MODERATE / CARDIO (70-80% of max HR): The 'cardio zone.' Improves cardiovascular fitness and aerobic capacity. You can talk in short sentences but can't hold a long conversation. Sustainable for 30-60 minutes.
ZONE 4 — HARD / THRESHOLD (80-90% of max HR): Lactate threshold zone. Builds speed and improves your body's ability to clear lactic acid. Sustainable for 10-20 minutes. Used in interval training.
ZONE 5 — MAXIMUM / PEAK (90-100% of max HR): All-out effort. Builds VO2 max and explosive power. Sustainable for only 1-5 minutes per interval. Used in high-intensity interval training (HIIT).
How the math works
Max HR is estimated as 220 minus age. Zones are percentages of that max. Karvonen adds resting HR to the math, which personalizes the target ranges based on your starting fitness.
Max HR · HRmax ≈ 220 − age
Percent of max · target = intensity × HRmax
Karvonen · target = resting + intensity × (HRmax − resting)
AHA moderate ~50 to 70% · vigorous ~70 to 85%.
Fat burning vs. cardio zones
The 'fat burning zone' (Zone 2, 60-70% of max HR) does use a higher PERCENTAGE of fat for fuel, but it burns FEWER total calories per minute than the cardio zone. The misleading name comes from this percentage-vs-total confusion.
Example: A 30-year-old (max HR 190) in Zone 2 (133 bpm) might burn 8 calories/minute with 50% from fat = 4 fat calories/minute. The same person in Zone 3 (152 bpm) might burn 12 calories/minute with 35% from fat = 4.2 fat calories/minute — slightly MORE fat burning despite the lower percentage.
For fat loss, total calorie burn matters more than the 'fat burning percentage.' Higher-intensity workouts in Zone 3-4 typically burn more total fat per workout, plus they keep your metabolism elevated for hours after.
Karvonen formula vs. simple formula
There are two primary ways to calculate target heart rate:
SIMPLE METHOD: Target HR = Max HR × intensity percentage
Example: A 30-year-old at 70% intensity = (220-30) × 0.70 = 133 bpm
KARVONEN FORMULA (more accurate): Target HR = ((Max HR - Resting HR) × intensity %) + Resting HR
Example: A 30-year-old with resting HR of 65 at 70% intensity = ((190-65) × 0.70) + 65 = 152 bpm
The Karvonen formula accounts for your individual resting heart rate, which varies based on fitness level. A highly fit person with a low resting HR gets a lower Karvonen target than someone with a higher resting HR at the same intensity percentage.
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Configure and track your physical training goals with these related health calculators:
Health note. Estimated heart rate zones are for general guidance. Consult a medical professional before starting any new or vigorous exercise program, particularly if you have cardiovascular conditions or take heart rate-altering medications.
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Frequently asked questions
The most common way to estimate maximum heart rate is 220 minus your age (in beats per minute). For a 40-year-old, the estimated max HR is 180 bpm. While useful as a starting point, individual actual max HR can vary by 10 to 15 bpm.
Zone 1 (very light) is 50-60% of max HR, Zone 2 (light/aerobic) is 60-70%, Zone 3 (moderate) is 70-80%, Zone 4 (hard/threshold) is 80-90%, and Zone 5 (maximum effort) is 90-100% of max HR.
The Karvonen formula calculates target heart rate by taking resting heart rate and heart-rate reserve (max HR minus resting HR) into account. The formula is: target HR = resting HR + (intensity % × reserve). This provides a more personalized target range based on your current cardiovascular fitness.
Zone 2 (60-70% of max HR) is often called the fat-burning zone because your body burns a higher percentage of calories from fat rather than carbohydrates. However, higher-intensity zones burn more total calories overall, which is often more effective for total fat loss.
Briefly reaching your max heart rate during intense intervals is generally safe for healthy individuals. However, you should not sustain maximum effort for long periods. If you have any underlying cardiovascular conditions, consult your doctor for custom guidelines.
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