How to Calculate a Target Heart Rate

by

Target Heart Rate Calculator

70%

Your Results:

Estimated Max Heart Rate (MHR): BPM

Heart Rate Reserve (HRR): BPM

Target Heart Rate: BPM

Recommended training range (50% – 85%): BPM

function calculateTHR() { var age = parseFloat(document.getElementById('age').value); var rhr = parseFloat(document.getElementById('restingHR').value); var intensity = parseFloat(document.getElementById('intensity').value) / 100; if (isNaN(age) || age 120) { alert("Please enter a valid age."); return; } if (isNaN(rhr) || rhr 120) { alert("Please enter a valid resting heart rate (typical range 40-100)."); return; } // MHR Formula (Fox Formula) var mhr = 220 – age; // Karvonen Formula: THR = ((MHR – RHR) * intensity) + RHR var hrr = mhr – rhr; var thr = Math.round((hrr * intensity) + rhr); var lowRange = Math.round((hrr * 0.50) + rhr); var highRange = Math.round((hrr * 0.85) + rhr); document.getElementById('mhr-output').innerText = mhr; document.getElementById('hrr-output').innerText = hrr; document.getElementById('thr-output').innerText = thr; document.getElementById('range-output').innerText = lowRange + " to " + highRange; document.getElementById('thr-result-container').style.display = 'block'; }

How to Calculate a Target Heart Rate

To maximize your cardiovascular benefits and ensure exercise safety, it is essential to know your target heart rate (THR). Calculating this allows you to monitor your effort levels and stay within a zone that improves aerobic capacity without overexerting the heart muscle.

The Karvonen Formula Explained

While the basic "220 minus age" formula is a quick estimate, the Karvonen Formula used in our calculator is widely considered more accurate because it accounts for your Resting Heart Rate (RHR). This measures your "Heart Rate Reserve" (the difference between your peak and your rest).

The math works as follows:

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

Understanding Heart Rate Intensity Zones

Depending on your fitness goals, you should aim for different intensity percentages:

  • Moderate Intensity (50-70%): Ideal for beginners, weight management, and long-duration endurance training.
  • Vigorous Intensity (70-85%): Best for improving athletic performance, increasing VO2 max, and high-intensity interval training (HIIT).
  • Maximum Effort (85%+): Generally reserved for short bursts of sprinting or competitive racing; should be approached with caution.

Real-World Example

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

  • MHR: 220 – 40 = 180 BPM
  • HRR: 180 – 60 = 120 BPM
  • Calculation: (120 × 0.70) + 60 = 84 + 60 = 144 BPM

Important Safety Considerations

Always consult with a healthcare professional before starting a new vigorous exercise program, especially if you have a history of heart conditions or are taking medications (like beta-blockers) that intentionally lower your heart rate. In such cases, the standard formulas may not apply accurately to your physiology.

Leave a Comment