Methodology: how the calculator works
Every number the calculator shows comes from a published formula. This page lists them so you can check the results or reproduce them yourself.
Maximum heart rate
Zone 2 ranges
The headline result uses Karvonen when a resting heart rate is entered (because it reflects individual fitness), and percentage of maximum otherwise.
Five-zone table
Zones 1–5 use 50–60%, 60–70%, 70–80%, 80–90% and 90–100% of maximum heart rate, or of heart rate reserve when resting heart rate is entered. Values are rounded to the nearest beat.
Why Zone 2 = 60–70%
This follows the common five-zone convention used by most fitness devices. Physiologically, Zone 2 is best defined as the intensity just below the first lactate or ventilatory threshold, which varies between individuals; the talk test is a practical way to locate it. For many people the 60–70% band and the talk-test boundary roughly coincide.
Limitations
- Age-based maximum heart rate formulas can be wrong by 10 beats per minute or more for an individual.
- Medications, illness, heat, altitude, dehydration and fatigue change heart rate.
- The calculator is not designed for children, pregnancy or people with heart conditions.
- Results are estimates for healthy adults and are not medical advice.
Privacy
Calculations run entirely in your browser. Nothing you enter is sent to us.
Medical note: This is general information, not medical advice. Heart rate formulas are estimates. If you have a heart condition, high blood pressure, diabetes, take medication that affects heart rate (such as beta-blockers), are pregnant, or are new to exercise, ask a doctor before changing your training. Stop and seek help if you feel chest pain, severe breathlessness, dizziness or palpitations. Full disclaimer.
Sources
- Tanaka H, Monahan KD, Seals DR. "Age-predicted maximal heart rate revisited." Journal of the American College of Cardiology 2001;37(1):153–156
- British Columbia Medical Journal, "The science of exercise prescription: Martti Karvonen and his contributions"
- Maffetone P, "The 180 Formula: Heart-rate monitoring for real aerobic training"
- American Heart Association, "Target Heart Rates Chart" (last reviewed Aug 2024)
- Pollock ML et al. "ACSM Position Stand: The recommended quantity and quality of exercise…" Medicine & Science in Sports & Exercise 1998;30(6):975–991
- American Council on Exercise, "Research on the Talk Test" (Foster & Porcari)