How to Calculate Target Heart Rate with the Karvonen Formula

If you want to understand exactly how your target heart rate zones are determined, nothing beats working through the calculation by hand. The Karvonen Formula (also called the Heart Rate Reserve method) gives you personalized zones by factoring in your resting heart rate. Below is a step-by-step guide to compute your target heart rate manually, along with two realistic examples and common mistakes to avoid.

Before you start, you may find it helpful to review What Is Target Heart Rate? or our detailed breakdown of the Karvonen Formula. For a quick reference on zone ranges, see the Target Heart Rate Zone Chart.

What You'll Need

• Your age (in years)
• Your resting heart rate (in beats per minute, bpm) – measure it first thing in the morning, before getting out of bed
• The desired exercise intensity as a percentage (e.g., 70%)
• A calculator or pen and paper for manual math
• (Optional) A list of the intensity percentages for your target zone(s) – e.g., 50–60% for warm-up, 60–70% for fat burn, etc.

Step-by-Step Instructions

1. Calculate your maximum heart rate (Max HR). Use the traditional formula:
   For men: Max HR = 220 – age
   For women: Max HR = 226 – age
   (These are the standard estimates; individual variation exists.)
2. Find your Heart Rate Reserve (HRR). HRR = Max HR – Resting HR.
3. Multiply HRR by the desired intensity (as a decimal). For example, 70% intensity = 0.70. So, HRR × 0.70.
4. Add your resting heart rate back. The formula is: Target HR = (HRR × Intensity) + Resting HR.
5. (Optional) Repeat for upper and lower zone boundaries. If you have a zone range (e.g., 60–70%), compute Target HR at 60% and at 70% to get the range.

Example 1: 30-Year-Old Man at 70% Intensity

• Age = 30, Resting HR = 70 bpm
• Max HR = 220 – 30 = 190 bpm
• HRR = 190 – 70 = 120 bpm
• Intensity = 70% = 0.70
• Target HR = (120 × 0.70) + 70 = 84 + 70 = 154 bpm

So for a moderate workout, this person should aim for about 154 bpm.

Example 2: 45-Year-Old Woman at 60% Intensity

• Age = 45, Resting HR = 65 bpm
• Max HR = 226 – 45 = 181 bpm
• HRR = 181 – 65 = 116 bpm
• Intensity = 60% = 0.60
• Target HR = (116 × 0.60) + 65 = 69.6 + 65 = 134.6 bpm (round to 135 bpm)

For fat‑burn or light cardio, 135 bpm is a good target.

Common Pitfalls to Avoid

• Using the wrong Max HR formula for your gender. Men use 220 – age, women use 226 – age. Mixing them gives an inaccurate baseline.
• Forgetting to convert percentage to decimal. Multiply by 0.70, not 70.
• Skipping the resting heart rate step. The Karvonen method relies on HRR; if you only take a percentage of Max HR, it’s a different (and often less accurate) method.
• Not adding back resting HR. The final result must include your resting heart rate; otherwise the number is too low.
• Using an inaccurate resting HR. Measure it on several mornings for a reliable average.

Mastering this manual calculation gives you a deeper understanding of how our Target Heart Rate Calculator works. For further guidance, visit our FAQ page or check the guide for women if you need more details on the female formula.