Performance
Generate precision heart rate zones using Tanaka, Fox, or field-test data. Perfect for HIIT, endurance base building, and prescribed rehab cardio blocks.
Heart rate is the number of contractions the heart makes per minute. Target heart rate training keeps your cardio sessions specific: easy days stay easy, threshold efforts push adaptation, and HIIT intervals fall into the red zone. This calculator pairs lab-grade formulas with resting heart rate adjustments to match your physiology.
Maximum heart rate (MHR) represents the highest heart beats per minute you can safely reach during maximal effort. Lab testing typically uses graded treadmill or cycle ergometer protocols. Because not everyone has lab access, the Tanaka, Fox, and Inbar formulas predict MHR from age with surprisingly tight accuracy bands (±10 bpm for most adults).
Resting heart rate (RHR) is measured immediately after waking, before caffeine or stress. Lower RHR usually signals better aerobic conditioning. Incorporating RHR unlocks the Karvonen method, which scales training zones to your heart rate reserve (MHR − RHR).
Measure for 60 seconds while seated and relaxed.
Heart rate reserve (HRR) = MHR − RHR. Multiply HRR by an intensity percentage, then add back RHR. The result is a target heart rate that reflects your cardiovascular baseline rather than population averages.
This calculator outputs both the %MHR ranges and Karvonen ranges so you can follow whichever system your coach, wearable device, or rehab protocol prefers.
Besides heart rate, athletes use perceived exertion, power meters, or pace charts. However, heart rate remains the most universal metric. Common lab-backed systems include:
Haskell & Fox
Quick heuristic for group classes and general fitness. Good starting point but less precise for trained endurance athletes or masters competitors.
Karvonen
Uses HRR to personalize training zones. Recommended for structured coaching, HIIT periodization, or return-to-play rehab because it reflects current conditioning.
Borg RPE Scale
Rate exertion on a 6-20 or 0-10 scale. Multiply the RPE by 10 to estimate heart rate. Useful when wearables misread (cold weather, wrist tattoos, swimming).
Talk Test
If you can speak full sentences, you're in Zones 1-2. Broken phrases indicate Zone 3, single words or no speech signal Zones 4-5. Old-school but reliable without gadgets.
Endurance athletes spend ~80% of weekly volume in Zones 1-2, ~15% in Zone 3, and sprinkle 5% in Zones 4-5. Strength athletes or HIIT-focused clients typically reverse that distribution. Monitor heart rate variability (HRV), perceived exertion, sleep, and fueling to decide when to push intensity or deload.
If you feel dizzy, experience chest pain, or your wearable reports erratic spikes, stop training and consult a medical professional. This tool is educational and not a diagnostic device.