Target Heart Rate Calculator
Find your personalised heart rate zones for fat burn, cardio, aerobic, anaerobic, and peak training using the Karvonen formula.
Frequently Asked Questions
How do I calculate my maximum heart rate?
The most widely used formula is Max HR = 220 − age. A 35-year-old's estimated max HR is 185 bpm. More accurate alternatives: Tanaka formula (208 − 0.7 × age) performs better for older adults; Gulati formula (206 − 0.88 × age) is validated for women. All formulas have a margin of error of ±10–20 bpm — the only way to find your true maximum is a supervised maximal exercise test.
What are the heart rate training zones?
Zone 1 (50–60% max HR): recovery/warm-up. Zone 2 (60–70%): fat burning, building aerobic base. Zone 3 (70–80%): aerobic fitness, "cardio" zone. Zone 4 (80–90%): anaerobic threshold, race-pace training. Zone 5 (90–100%): peak/sprint, sustainable only briefly. Most endurance coaches recommend spending 80% of training time in Zone 2 and 20% in Zones 4–5 (the "80/20 rule").
What is the Karvonen formula and why is it more accurate?
The Karvonen formula calculates Target HR = ((Max HR − Resting HR) × intensity%) + Resting HR. By incorporating your resting heart rate (heart rate reserve), it personalises zones to your individual fitness level. A fit person with a resting HR of 45 bpm has a higher heart rate reserve than an unfit person at 75 bpm, so the same percentage of max HR means different things — Karvonen corrects for this.
Which heart rate zone is best for burning fat?
The fat-burn zone (60–70% max HR) uses a higher proportion of fat as fuel (~60% fat vs 40% carbs) compared to higher intensities. However, higher-intensity training burns far more total calories — 40 minutes in Zone 4 may burn twice as many calories as the same time in Zone 2. For weight loss, total calorie expenditure matters more than fat percentage; for metabolic health and endurance base, Zone 2 training is uniquely effective.
How do I measure my resting heart rate accurately?
Measure resting heart rate first thing in the morning, before getting out of bed, on at least 3 consecutive days and average the results. Normal adult resting HR is 60–100 bpm; highly trained athletes often achieve 40–50 bpm or even lower. A resting HR under 60 (bradycardia) in athletes is healthy; in sedentary individuals it may warrant investigation. Track it over time — a rising resting HR can signal overtraining, illness, or poor recovery.