Resting Heart Rate Target Heart Rate Calculator

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Target Heart Rate Calculator (Karvonen Method)

Calculate your ideal heart rate zones based on your resting heart rate and age.

Your Heart Rate Data

Estimated Max Heart Rate (MHR): 0 BPM
Heart Rate Reserve (HRR): 0 BPM
Target Zone Lower Limit: 0 BPM
Target Zone Upper Limit: 0 BPM

*These calculations are based on the Karvonen Formula, which accounts for your unique fitness level via your resting heart rate.

Understanding Your Heart Rate

Monitoring your heart rate is one of the most effective ways to gauge exercise intensity and track cardiovascular health. Unlike basic formulas that only use age, this calculator uses the Karvonen Formula, which incorporates your Resting Heart Rate (RHR) for a more personalized result.

What is Resting Heart Rate (RHR)?

Your resting heart rate is the number of times your heart beats per minute while you are at complete rest. For most healthy adults, a normal RHR ranges from 60 to 100 beats per minute (BPM). Athletes often have lower RHRs, sometimes in the 40s or 50s, because their heart muscle is more efficient.

The Karvonen Formula Explained

The Karvonen Formula is widely considered more accurate than the standard "220 minus age" formula because it calculates your Heart Rate Reserve (HRR). HRR is the difference between your maximum heart rate and your resting heart rate.

The Math:
1. Max Heart Rate (MHR) = 220 – Age
2. Heart Rate Reserve (HRR) = MHR – Resting Heart Rate
3. Target Heart Rate = (HRR × Intensity%) + Resting Heart Rate

Exercise Intensity Zones

Intensity Level Percentage Range Benefit
Moderate Intensity 50% – 70% Weight management, basic endurance, and health maintenance.
Vigorous Intensity 70% – 85% Improved aerobic capacity and cardiovascular fitness.
Maximum Effort 85% – 100% High-intensity interval training (HIIT) and peak performance.

Realistic Example

Suppose you are a 40-year-old with a resting heart rate of 70 BPM and you want to exercise at 60% intensity.

  • Max HR: 220 – 40 = 180 BPM
  • Heart Rate Reserve: 180 – 70 = 110 BPM
  • Target HR: (110 × 0.60) + 70 = 136 BPM

In this example, your target heart rate for a 60% intensity workout would be 136 beats per minute.

function calculateHeartRate() { var age = parseFloat(document.getElementById('hr_age').value); var restingHR = parseFloat(document.getElementById('hr_resting').value); var intensityLow = parseFloat(document.getElementById('hr_intensity_low').value) / 100; var intensityHigh = parseFloat(document.getElementById('hr_intensity_high').value) / 100; if (isNaN(age) || isNaN(restingHR) || age <= 0 || restingHR 120) { alert("Please enter a realistic age."); return; } // 1. Calculate Max Heart Rate (MHR) var mhr = 220 – age; if (restingHR >= mhr) { alert("Resting heart rate cannot be higher than or equal to maximum heart rate. Please check your inputs."); return; } // 2. Calculate Heart Rate Reserve (HRR) var hrr = mhr – restingHR; // 3. Calculate Target Heart Rates using Karvonen Formula var targetLow = (hrr * intensityLow) + restingHR; var targetHigh = (hrr * intensityHigh) + restingHR; // Display Results document.getElementById('res_mhr').innerHTML = Math.round(mhr) + " BPM"; document.getElementById('res_hrr').innerHTML = Math.round(hrr) + " BPM"; document.getElementById('res_target_low').innerHTML = Math.round(targetLow) + " BPM"; document.getElementById('res_target_high').innerHTML = Math.round(targetHigh) + " BPM"; // Show result box document.getElementById('hr_result_box').style.display = 'block'; }

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