Hiit Cardio Heart Rate Calculator

HIIT Cardio Heart Rate Calculator

Measure this in the morning while seated and calm.

Your HIIT Target Zones

Estimated Max Heart Rate:
Work Phase (High Intensity):
Recovery Phase (Active Rest):

Note: These targets are calculated using the Karvonen Formula for higher accuracy.


How to Use the HIIT Cardio Heart Rate Calculator

High-Intensity Interval Training (HIIT) is defined by its alternating periods of maximum effort and low-intensity recovery. To get the most out of your workout, you need to ensure you are pushing hard enough during the "work" phase and letting your heart rate drop enough during the "rest" phase. This calculator uses the Karvonen Formula, which accounts for your resting heart rate to provide more personalized and accurate zones than age-based formulas alone.

The Calculation Logic

Our calculator follows these steps to determine your optimal training zones:

  1. Max Heart Rate (MHR): Calculated as 220 minus your age.
  2. Heart Rate Reserve (HRR): Your Max HR minus your Resting HR.
  3. Target Work Zone: (HRR × Work Intensity %) + Resting HR.
  4. Target Recovery Zone: (HRR × Recovery Intensity %) + Resting HR.

Understanding HIIT Zones

For a true HIIT session, your "Work" phase should typically fall between 80% and 95% of your heart rate reserve. This is the zone where you improve cardiovascular capacity and trigger the "afterburn" effect (EPOC). The "Recovery" phase should drop to 40% to 55%, allowing your body to clear some lactic acid before the next sprint.

Example Scenario:

User: 30 years old, 60 BPM Resting Heart Rate.
Max Heart Rate: 190 BPM.
Heart Rate Reserve: 130 BPM.
Work Zone (90%): ((130 * 0.90) + 60) = 177 BPM.
Rest Zone (50%): ((130 * 0.50) + 60) = 125 BPM.

Why Resting Heart Rate Matters

Most generic calculators ignore your resting heart rate. However, a person with a resting heart rate of 50 BPM is significantly more fit than someone with 80 BPM. By including this metric, the Karvonen formula adjusts the "intensity" to your actual fitness level, ensuring your HIIT sessions are safe yet challenging.

function calculateHIITZones() { var age = document.getElementById("hiit_age").value; var restingHR = document.getElementById("hiit_resting_hr").value; var workPerc = document.getElementById("hiit_work_intensity").value; var restPerc = document.getElementById("hiit_recovery_intensity").value; // Validation if (!age || age 120) { alert("Please enter a valid age."); return; } if (!restingHR || restingHR 200) { alert("Please enter a valid resting heart rate."); return; } var ageNum = parseFloat(age); var restHRNum = parseFloat(restingHR); var workIntensity = parseFloat(workPerc) / 100; var restIntensity = parseFloat(restPerc) / 100; // Formulas var maxHR = 220 – ageNum; var hrReserve = maxHR – restHRNum; if (hrReserve <= 0) { alert("Resting heart rate cannot be higher than maximum heart rate. Please check your inputs."); return; } var targetWork = (hrReserve * workIntensity) + restHRNum; var targetRest = (hrReserve * restIntensity) + restHRNum; // Rounding var maxHR_final = Math.round(maxHR); var targetWork_final = Math.round(targetWork); var targetRest_final = Math.round(targetRest); // Display document.getElementById("res_max_hr").innerHTML = maxHR_final + " BPM"; document.getElementById("res_work_hr").innerHTML = targetWork_final + " BPM"; document.getElementById("res_rest_hr").innerHTML = targetRest_final + " BPM"; document.getElementById("hiit_result_container").style.display = "block"; // Smooth scroll to result document.getElementById("hiit_result_container").scrollIntoView({ behavior: 'smooth', block: 'nearest' }); }

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