How this HIIT target heart rate calculator works
The tool estimates maximum heart rate, subtracts resting heart rate to obtain heart-rate reserve, then applies intensity percentages before adding resting heart rate back. This Karvonen approach responds to resting fitness, but it still depends on an estimated maximum.
heart-rate reserve = estimated maximum HR − resting HRtarget HR = resting HR + (heart-rate reserve × intensity)Tanaka maximum estimate = 208 − (0.7 × age)Understanding your results
AHA describes moderate activity as roughly 50%–70% and vigorous activity as roughly 70%–85% of age-predicted maximum using its simpler chart. This tool uses heart-rate reserve bands, so the numbers will differ. The HIIT band is an advanced planning estimate, not an instruction to reach 95%.
Why “220 minus age” is limited
Age formulas describe averages and can miss an individual maximum by a meaningful margin. Fitness, genetics, heat, dehydration, altitude, illness, fatigue, caffeine, and measurement error also affect exercise heart rate.
Medication and heart conditions
Beta blockers and other medications may blunt heart rate. Arrhythmia, cardiovascular disease, autonomic disorders, pregnancy, recent illness, or rehabilitation can make generic zones inappropriate. Use clinician-prescribed limits when available.
Frequently asked questions about HIIT heart rate
What heart rate zone is HIIT?
HIIT alternates hard work with recovery, but the correct intensity is individual. This calculator labels 85%–95% of heart-rate reserve as an advanced work interval estimate. Beginners and people with medical risks should not treat that band as a required target.
Is Karvonen better than 220 minus age?
Karvonen incorporates resting heart rate, which can personalize intensity bands, but it still needs an estimated or measured maximum. It is not automatically more accurate for every person, and neither method replaces exercise testing or clinician-set zones.
What is a fat-burning zone?
Lower intensities may use a greater proportion of fat as fuel, but total energy use, duration, fitness, and diet affect body-fat change. A “fat-burning zone” does not guarantee more fat loss and should not replace a balanced training plan.