How to use the target heart rate calculator
- Enter your age in years.
- Enter your resting heart rate in beats per minute (measure it first thing in the morning).
- Optionally, enter a custom intensity percentage for a specific workout goal.
- Read your five heart rate zones and the custom zone if provided.
How the Karvonen Formula Works
The Karvonen formula calculates your target heart rate by factoring in your resting heart rate, which makes it more accurate than simply taking a percentage of your maximum heart rate. The steps are:
- Estimate maximum heart rate (MHR):
220 - age - Calculate heart rate reserve (HRR):
MHR - resting heart rate - Apply the desired intensity:
(HRR × intensity) + resting heart rate
For example, a 30-year-old with a resting heart rate of 65 bpm exercising at 70% intensity would compute: MHR = 190, HRR = 125, and target = (125 × 0.70) + 65 = 152.5, rounded to 153 bpm. This target heart rate calculator applies that math across five standard zones automatically.
Standard Heart Rate Zones
Exercise physiologists generally divide effort into five zones. Each serves a different training purpose, from active recovery to peak performance.
| Zone | Intensity | Purpose |
|---|---|---|
| Zone 1 | 50 to 60% | Very light effort, warm-up, cool-down, active recovery |
| Zone 2 | 60 to 70% | Light aerobic work, fat oxidation, building an endurance base |
| Zone 3 | 70 to 80% | Moderate aerobic fitness, improving cardiovascular efficiency |
| Zone 4 | 80 to 90% | Hard anaerobic threshold work, increasing lactate tolerance |
| Zone 5 | 90 to 100% | Maximum effort, short intervals, sprint training |
Most training plans recommend spending the majority of your time in Zone 2, with one or two sessions per week in Zones 4 and 5.
Measuring Your Resting Heart Rate
Your resting heart rate (RHR) is the number of times your heart beats per minute while completely at rest. For the most reliable input into this target heart rate calculator, measure it immediately after waking up, before sitting up or drinking coffee.
Place two fingers on your radial artery at the wrist or your carotid artery on the neck. Count the beats for 60 seconds, or count for 15 seconds and multiply by four. A typical adult RHR falls between 60 and 100 bpm. Well-trained endurance athletes often have a resting heart rate below 50 bpm due to higher stroke volume.
If your RHR varies day to day, take a three-day average. Illness, poor sleep, dehydration and stress can temporarily elevate your resting rate by 5 to 10 bpm.
Karvonen vs Simple Percentage Methods
A simpler method estimates exercise zones by multiplying your maximum heart rate directly by a percentage. For a 30-year-old at 70%, that yields 190 × 0.70 = 133 bpm. The Karvonen formula gives (125 × 0.70) + 65 = 153 bpm.
The difference matters because the simple method ignores your baseline fitness. Two people of the same age but different resting heart rates will have different actual physiological loads at the same absolute heart rate. By anchoring the calculation to your heart rate reserve, the Karvonen formula scales the intensity proportionally to your individual capacity.
This is why coaches and sports medicine professionals prefer the Karvonen approach when prescribing exercise intensities.
Limitations and Safety Notes
The standard 220 - age equation for maximum heart rate is a population average. Individual maximums can vary by 10 to 15 bpm in either direction. More refined formulas exist, such as Tanaka (208 - 0.7 × age), but they still represent statistical estimates rather than precise personal limits.
Certain medications, particularly beta-blockers, artificially lower both resting and maximum heart rates. If you take heart medication, the zones produced by any target heart rate calculator may not apply to you. Consult your physician before starting a new exercise program, especially if you have a history of cardiovascular issues.
Heart rate monitors worn on the wrist can be less accurate than chest straps during high-intensity intervals due to motion artifacts. Verify unusual readings manually.
An estimate, not medical advice
The target heart rate calculator uses a standard published formula, and formulas describe averages, not you. Age, body composition, medical conditions, medication, pregnancy and training history can all move the real number. Use the result as a starting point for planning, and speak to a doctor, dietitian or qualified coach before making health, diet or training decisions, especially if you have a medical condition.
Worked examples
Each result below was produced by the same code the tool runs, so you can check your own numbers against them.
| Example | Input | Result |
|---|---|---|
| Average 30-year-old | Age (years): 30; Resting heart rate (bpm): 65 | Max heart rate: 190 bpm; Heart rate reserve: 125 bpm; Zone 1 (50-60%): 128 to 140 bpm; Zone 2 (60-70%): 140 to 153 bpm; Zone 3 (70-80%): 153 to 165 bpm; Zone 4 (80-90%): 165 to 178 bpm; Zone 5 (90-100%): 178 to 190 bpm |
| Older adult, lower resting rate | Age (years): 60; Resting heart rate (bpm): 58 | Max heart rate: 160 bpm; Heart rate reserve: 102 bpm; Zone 1 (50-60%): 109 to 119 bpm; Zone 2 (60-70%): 119 to 129 bpm; Zone 3 (70-80%): 129 to 140 bpm; Zone 4 (80-90%): 140 to 150 bpm; Zone 5 (90-100%): 150 to 160 bpm |
| Young athlete at 80% intensity | Age (years): 22; Resting heart rate (bpm): 48; Custom intensity (%): 80 | Max heart rate: 198 bpm; Heart rate reserve: 150 bpm; Zone 1 (50-60%): 123 to 138 bpm; Zone 2 (60-70%): 138 to 153 bpm; Zone 3 (70-80%): 153 to 168 bpm; Zone 4 (80-90%): 168 to 183 bpm; Zone 5 (90-100%): 183 to 198 bpm; Custom (80%): 168 bpm |
| Beginner runner | Age (years): 45; Resting heart rate (bpm): 72; Custom intensity (%): 60 | Max heart rate: 175 bpm; Heart rate reserve: 103 bpm; Zone 1 (50-60%): 124 to 134 bpm; Zone 2 (60-70%): 134 to 144 bpm; Zone 3 (70-80%): 144 to 154 bpm; Zone 4 (80-90%): 154 to 165 bpm; Zone 5 (90-100%): 165 to 175 bpm; Custom (60%): 134 bpm |
FAQ
What is a good target heart rate for exercise?
For moderate-intensity exercise, aim for 60 to 70% of your heart rate reserve (Zone 2). For vigorous exercise, aim for 70 to 85%. Use this target heart rate calculator to find the exact beats per minute for your age and resting rate.
Why does the Karvonen formula use resting heart rate?
Resting heart rate reflects your baseline cardiovascular fitness. By subtracting it from your maximum, the formula isolates your heart rate reserve, ensuring the calculated zones match your actual physiological capacity rather than just your age.
Is the 220 minus age formula accurate?
It provides a reasonable estimate for the general population, but individual maximum heart rates can differ by 10 to 15 bpm. For precise training zones, a supervised maximal exercise test is the gold standard.
Can I use this tool if I take beta-blockers?
Beta-blockers lower your heart rate significantly, making standard formulas unreliable. Consult your doctor for personalized exercise intensity guidelines rather than relying solely on a calculator.
How do I know my resting heart rate?
Count your pulse for 60 seconds immediately after waking up, before getting out of bed. Do this for three consecutive mornings and average the results for the most accurate number.
Which heart rate zone burns the most fat?
Zone 2 (60 to 70% intensity) uses the highest percentage of fat as fuel. However, higher-intensity zones burn more total calories per minute, which also contributes to overall fat loss over time.