About target heart rate
Your target heart rate is the beats-per-minute range you aim to keep your pulse within during exercise so the effort is hard enough to improve fitness but not so hard that it becomes unsafe or unsustainable. It is anchored to your estimated maximum heart rate — the fastest your heart can beat — and expressed as a percentage of that maximum, or of your heart-rate reserve. Training inside a defined zone lets you match effort to a goal, whether that is fat-burning, aerobic endurance, or high-intensity intervals.
The two formulas this calculator uses
The percentage-of-max method is the simplest: it estimates maximum heart rate as 220 − age and multiplies that by your target intensity. A 30-year-old has an estimated max of 190 bpm, so a 70% target is 190 × 0.70 = 133 bpm.
The Karvonen method (heart-rate reserve method) is more individualized because it accounts for fitness through resting heart rate:
Target HR = ((Max HR − Resting HR) × Intensity%) + Resting HR
Max HR − Resting HR is your heart-rate reserve. For the same 30-year-old with a resting pulse of 65 bpm, the reserve is 190 − 65 = 125 bpm, and a 70% target is (125 × 0.70) + 65 = 152 bpm. The Karvonen figure is higher because a fit person spends a larger share of each exercise session above their low resting baseline.
Common training zones
- 50–60% (very light / warm-up): recovery and getting started; you can hold a full conversation.
- 60–70% (light / fat-burn): builds base aerobic fitness; a large share of calories come from fat.
- 70–80% (moderate / aerobic): the endurance-building zone; improves cardiovascular and respiratory capacity.
- 80–90% (hard / anaerobic threshold): raises lactate threshold and speed; conversation becomes difficult.
- 90–100% (maximum): short interval efforts only, for experienced athletes.
The American Heart Association defines moderate-intensity activity as 50–70% of maximum heart rate and vigorous activity as 70–85%.
Accuracy and individual variation
- The 220 − age formula is a population average with a standard deviation of roughly ±10–12 bpm, so your true maximum may be well above or below the estimate. A lab or field max-HR test gives a more accurate number.
- Alternative max-HR formulas exist — Tanaka (208 − 0.7 × age) tends to fit older adults better, and Gulati (206 − 0.88 × age) was derived specifically for women.
- Measure resting heart rate first thing in the morning, before getting out of bed, averaged over several days. Caffeine, stress, dehydration, and medications (especially beta-blockers) can shift both resting and maximum heart rate substantially.