Target Heart Rate Calculator

What Is the Karvonen Formula?

The Karvonen method is a popular way to calculate target heart rate zones because it factors in your resting heart rate, making it more personalised than simply using a percentage of your maximum heart rate. The formula is:

Target HR = ((Max HR − Resting HR) × intensity %) + Resting HR

Where Max HR is estimated as 220 − age, and the intensity percentage corresponds to the training zone you want to target.

The Five Training Zones

• Zone 1 — Very Light (50–60%): Recovery and warm-up. Improves overall health with minimal strain.
• Zone 2 — Light (60–70%): Aerobic base building. Fat-burning and endurance; the bulk of easy training.
• Zone 3 — Moderate (70–80%): Cardiovascular fitness. Improves aerobic capacity and efficiency.
• Zone 4 — Hard (80–90%): Anaerobic threshold. Boosts lactate threshold and race pace.
• Zone 5 — Max (90–100%): Peak intensity. Short bursts for maximum performance; use sparingly.

How to Measure Resting Heart Rate

Measure your resting heart rate first thing in the morning before getting out of bed. Find your pulse on your wrist or neck, count the beats for 60 seconds (or 30 seconds and multiply by 2). For accuracy, measure over several days and take the average. A typical resting HR is 60–80 bpm; well-trained athletes may be as low as 40–50 bpm.

Training Tips

Spend most of your training time in Zones 2 and 3 to build a strong aerobic base, then add Zone 4 intervals to raise your threshold. Use Zone 5 sparingly for short, high-intensity efforts. Always include recovery sessions in Zone 1. Remember that heart rate varies with hydration, temperature, stress, and caffeine, so trends matter more than single readings.