STEADFAST • CARDIO TOOLSUnderstand your effort.
Estimate heart rate training zones or explore a custom range using heart rate reserve.
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How the general zones work
Estimated maximum heart rate = 220 − age. The general zones use the American Heart Association’s guide: moderate activity at approximately 50% to 70% of maximum and vigorous activity at approximately 70% to 85%. The shared boundary is intentional. These are population estimates, not measured personal thresholds or a safe upper limit. AHA target heart rate guide.
What heart rate reserve adds
Heart rate reserve = maximum heart rate − resting heart rate. The Karvonen calculation is resting heart rate + (reserve × chosen percentage). A percentage of reserve is not interchangeable with the same percentage of maximum. For example, a maximum of 180 and resting rate of 60 give a reserve of 120. At 50% of reserve, the result is 120 bpm; at 50% of maximum, it is 90 bpm. Heart rate reserve explained by Cleveland Clinic.
Use consistent measurements
Measure your resting pulse while calm and rested. Count for 30 seconds and double it, or count for a full minute. A peak recorded during an ordinary workout is not necessarily your maximum. Do not attempt an all out test just to fill in this calculator. Results are rounded to whole beats per minute.
Medication, medical limits, and perceived effort
Beta blockers and other medicines can change your heart rate response. If you have a heart condition or prescribed limits, use the guidance from your clinician instead of these generic calculations. Being below an estimated maximum does not establish that exercise is safe. AHA guidance on beta blockers and exercise.
For general moderate activity, you should still be able to talk. Use how you feel alongside the numbers. Stop exercising and seek medical attention for chest pain, faintness, or unusual severe breathlessness.
Is this my Zone 2?
This tool does not measure your physiological thresholds. Different zone systems use different definitions, so a watch’s Zone 2 may not match these ranges. Treat the output as a reference for discussion and planning.
Plan your training with Steadfast
For adults aged 18 to 100. The entered calculator values are processed in your browser and are not submitted by this tool.