How to Calculate Your Target Heart Rate Range

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Target Heart Rate Calculator

Measure this in the morning before getting out of bed.
Estimated Max Heart Rate: —
Moderate Intensity (50-70%): —
Vigorous Intensity (70-85%): —
*Calculated using the Karvonen Formula (Heart Rate Reserve method).
function calculateHeartRate() { var age = parseFloat(document.getElementById('user_age').value); var rhr = parseFloat(document.getElementById('user_rhr').value); var resultArea = document.getElementById('thr-result-area'); if (isNaN(age) || age 120) { alert("Please enter a valid age."); return; } if (isNaN(rhr) || rhr 220) { alert("Please enter a valid resting heart rate."); return; } var maxHR = 220 – age; var hrr = maxHR – rhr; // Karvonen Formula: Target Heart Rate = ((Max HR − Resting HR) × %Intensity) + Resting HR var modLow = Math.round((hrr * 0.50) + rhr); var modHigh = Math.round((hrr * 0.70) + rhr); var vigLow = Math.round((hrr * 0.70) + rhr); var vigHigh = Math.round((hrr * 0.85) + rhr); document.getElementById('res_max').innerHTML = maxHR + " bpm"; document.getElementById('res_mod').innerHTML = modLow + " – " + modHigh + " bpm"; document.getElementById('res_vig').innerHTML = vigLow + " – " + vigHigh + " bpm"; resultArea.style.display = 'block'; }

How to Calculate Your Target Heart Rate Range for Fitness

Understanding your target heart rate (THR) is essential for optimizing your cardiovascular workouts. Whether you are training for a marathon or simply trying to improve your general health, staying within specific heart rate zones ensures you are working hard enough to see results without overtraining or risking injury.

The Science of Heart Rate Zones

Heart rate zones are divided into intensity levels based on your Maximum Heart Rate (MHR). The two most common zones recommended by health organizations like the American Heart Association are:

  • Moderate Intensity: 50% to 70% of your maximum heart rate. Activities include brisk walking, doubles tennis, or light cycling.
  • Vigorous Intensity: 70% to 85% of your maximum heart rate. Activities include running, swimming laps, or HIIT workouts.

How the Karvonen Formula Works

While the basic formula for MHR is simply 220 minus your age, the Karvonen Formula used in our calculator above is considered more accurate by fitness professionals. It incorporates your Resting Heart Rate (RHR) to calculate your Heart Rate Reserve (HRR).

The math follows this sequence:

  1. Subtract your age from 220 to find Maximum Heart Rate.
  2. Subtract your Resting Heart Rate from your Maximum Heart Rate to find your Heart Rate Reserve (HRR).
  3. Multiply your HRR by your percentage of intensity (e.g., 0.50 for 50%).
  4. Add your Resting Heart Rate back to that number to get your final target BPM.

Example Calculation

Imagine a 40-year-old with a resting heart rate of 60 bpm who wants to exercise at 70% intensity:

  • Max HR: 220 – 40 = 180 bpm
  • HRR: 180 – 60 = 120 bpm
  • Intensity Calculation: (120 * 0.70) = 84
  • Target Heart Rate: 84 + 60 = 144 bpm

How to Measure Your Resting Heart Rate

To get the most accurate results from this calculator, you need a precise resting heart rate. The best time to measure this is first thing in the morning, immediately after waking up and before consuming caffeine. Place two fingers on your wrist (radial pulse) or neck (carotid pulse), count the beats for 60 seconds, and use that number as your RHR.

Why Stay Within Your Range?

Training below your target range may result in fewer cardiovascular gains, while consistently training above 85% (the "Red Line" zone) can lead to rapid fatigue, lactic acid buildup, and increased risk of cardiac events for those not conditioned for high-intensity athletics. By monitoring your heart rate using a chest strap or smartwatch, you can adjust your pace in real-time to stay in the "Sweet Spot" for fat burning or aerobic conditioning.

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