Hiit Heart Rate Calculator

HIIT Heart Rate Zone Calculator

Calculate your optimal intensity zones for High-Intensity Interval Training using the Karvonen Formula.

function calculateHIITZones() { var age = parseFloat(document.getElementById('hiit_age').value); var rhr = parseFloat(document.getElementById('hiit_rhr').value); if (isNaN(age) || age 120) { alert("Please enter a valid age."); return; } if (isNaN(rhr) || rhr 120) { alert("Please enter a realistic resting heart rate (usually 40-100 BPM)."); return; } // Calculations based on Karvonen Formula var mhr = 220 – age; var hrr = mhr – rhr; var zone80 = Math.round((hrr * 0.80) + rhr); var zone90 = Math.round((hrr * 0.90) + rhr); var zone95 = Math.round((hrr * 0.95) + rhr); document.getElementById('res_mhr').innerHTML = mhr + " BPM"; document.getElementById('res_hrr').innerHTML = hrr + " BPM"; document.getElementById('res_80').innerHTML = zone80 + " BPM"; document.getElementById('res_90').innerHTML = zone90 + " BPM"; document.getElementById('res_95').innerHTML = zone95 + " BPM"; document.getElementById('hiit_results_box').style.display = 'block'; }

What is a HIIT Heart Rate?

High-Intensity Interval Training (HIIT) relies on pushing your cardiovascular system to its upper limits for short bursts of time. To be considered true HIIT, your heart rate should typically reach between 80% and 95% of your Maximum Heart Rate (MHR) during the "work" intervals.

The Karvonen Formula vs. Simple Percentage

While many calculators simply take a percentage of (220 – age), this HIIT Heart Rate Calculator uses the Karvonen Formula. This method is more accurate because it incorporates your Resting Heart Rate (RHR) to determine your Heart Rate Reserve (HRR). HRR reflects the actual range available for exercise, making the target zones personalized to your current fitness level.

Why Monitoring Heart Rate is Critical for HIIT

Training at the correct intensity ensures you trigger the Excess Post-exercise Oxygen Consumption (EPOC) effect, often called the "afterburn." If your heart rate is too low (below 80%), you are performing vigorous steady-state cardio rather than HIIT. If you consistently exceed 95%, you risk overtraining or injury.

Example HIIT Heart Rate Calculation

Imagine a 30-year-old individual with a resting heart rate of 60 BPM:

• Max Heart Rate: 220 – 30 = 190 BPM
• Heart Rate Reserve: 190 – 60 = 130 BPM
• 80% HIIT Zone: (130 * 0.80) + 60 = 164 BPM
• 95% HIIT Zone: (130 * 0.95) + 60 = 183 BPM

For this individual, the target "work" intervals should aim to keep the heart rate between 164 and 183 beats per minute.

Training Tips for HIIT Success

1. Warm Up: Never jump straight into a 90% intensity sprint. Spend at least 5-10 minutes gradually raising your heart rate.

2. Recovery Matters: During the "rest" intervals, your heart rate should drop. If it stays above 80% during rest, you may need to extend your recovery time or reduce the intensity of the work phase.

3. Listen to Your Body: Formulas provide a mathematical estimate. If you feel dizzy, nauseous, or experience chest pain, stop immediately, regardless of what your heart rate monitor says.

4. Use a Chest Strap: For HIIT, chest strap monitors are generally more accurate than wrist-based optical sensors, which can struggle to track rapid heart rate fluctuations during short intervals.