Target Heart Rate Calculator

How to use this calculator

1. Enter your age.
2. Optionally enter your resting heart rate — measured first thing in the morning before getting out of bed, or from your Apple Watch health data. This enables the more precise Karvonen formula.
3. Click Calculate Heart Rate Zones.

Tip: If you don't know your resting heart rate, leave it blank — the calculator falls back to the standard age-based formula, which is still a good starting point.

How it works

Maximum heart rate and the Karvonen formula

Maximum heart rate (MHR) is estimated using the Tanaka formula: MHR = 208 − (0.7 × age) — validated by Tanaka, Monahan, and Seals (2001, Journal of the American College of Cardiology) as more accurate than the older 220 − age rule, particularly for adults over 40. When a resting heart rate (RHR) is provided, zones use the Karvonen formula: Target HR = ((MHR − RHR) × intensity%) + RHR. This accounts for individual cardiovascular fitness — a person with a lower resting heart rate has a larger heart rate reserve and will calculate different zone boundaries than someone with the same age and a higher resting rate.

What the zones mean

The five zones are based on percentage of maximum heart rate and are widely used in exercise physiology for structuring training. Zone 1 (50–60%) — warm up: easy movement, recovery walks. Zone 2 (60–70%) — fat burn: the aerobic base zone, where fat is the primary fuel; corresponds to brisk walking for most adults. Zone 3 (70–80%) — cardio/aerobic: moderate intensity, improves cardiovascular fitness; brisk to power walking and jogging. Zone 4 (80–90%) — threshold: vigorous effort, improves lactate threshold. Zone 5 (90–100%) — peak: maximum effort, unsustainable for more than short intervals. For general health, the CDC recommends spending most exercise time in Zones 2–3.

Track it with StepGoals

Walking pace is a practical proxy for heart rate zone when you don't have a heart rate monitor. Research from Tudor-Locke and colleagues established that brisk walking at 100+ steps per minute consistently places most adults in Zone 2–3 (60–80% of max HR) — the range the CDC targets for moderate-intensity aerobic benefit. StepGoals' GPS Sessions show your live steps per minute during a walk, giving you a real-time indicator of your effort level without needing to check your wrist.

If you use an Apple Watch, heart rate data is written to Apple Health and available through the Health app alongside your step data. You can use the zones calculated here to evaluate whether your typical walking pace is keeping you in a meaningful cardiovascular zone — and use the Walking & Running Pace Calculator to find what pace corresponds to your target effort level.