Heart Rate Zone Calculator — Garmin-Style HR Zones

Age

Max HR Method

220 − Age

Simple and widely used

Tanaka (208 − 0.7 × Age)

More accurate for older athletes

I know my max HR

From a VO2max test or hard effort

Use Karvonen Formula

Accounts for your resting HR for more personalised zones

Zone Scheme

Enter your age to calculate zones

Optionally add your resting heart rate for more personalised results using the Karvonen formula.

Understanding Heart Rate Training Zones

Training in the right heart rate zone is one of the most effective ways to structure your workout programme. Each zone targets a different energy system, delivering different physiological adaptations.

The Three Max HR Formulas

220 − Age (Fox Formula)

The most widely known formula. Simple and easy to use, though it has a standard deviation of ±10–12 bpm, meaning it can be significantly off for individuals who are very fit or unfit. Best for: quick estimates when you don't have lab data.

Tanaka Formula (208 − 0.7 × Age)

Published in 2001 after a meta-analysis of 351 studies with over 18,000 subjects. Shown to be more accurate than the 220-age formula, especially for adults over 40. The equation reflects that max HR decreases more slowly with age than the Fox formula suggests. Best for: adults over 40 who train regularly.

Karvonen Formula (Heart Rate Reserve)

The Karvonen formula accounts for your resting heart rate (RHR) by working with your heart rate reserve — the difference between your max HR and your RHR. The formula for a target intensity is: target = ((maxHR − restHR) × intensity%) + restHR. This produces more personalised zones since a fit person with a low resting HR will have different zones from a sedentary person of the same age and max HR. Best for: athletes who know their resting HR and want the most personalised zones.

The 5-Zone Garmin Model

Garmin devices use a 5-zone model based on percentages of max HR. These match the zones this calculator produces and can be entered directly into the Garmin Connect app under User Settings → Heart Rate Zones. Each zone produces a different physiological response:

Zone 1 (50–60%) — Recovery and warm-up. Burns mostly fat. Very easy conversation.
Zone 2 (60–70%) — Aerobic base building. The "magic zone" for endurance development and fat burning.
Zone 3 (70–80%) — Aerobic fitness. Moderate effort. Improves cardiovascular efficiency.
Zone 4 (80–90%) — Lactate threshold. Very hard effort. Trains the body to clear lactic acid faster.
Zone 5 (90–100%) — VO2max and max effort. Anaerobic. Short-duration, maximum intensity intervals.

How to Find Your True Max HR

Formulas are estimates. The most accurate way to find your max HR is to measure it directly. Options include a VO2max test in a lab, a graded exercise test on a treadmill, or a hard racing effort with a heart rate monitor. Once you have a measured value, use the "I know my max HR" option above for the most accurate zones.

Zone 2 Training — Why It Matters

Elite endurance athletes spend 75–80% of their training volume in zone 2. At this intensity, the body adapts by increasing mitochondrial density, improving fat oxidation, and building capillary networks in the muscles. The result is a higher aerobic ceiling — you can go faster at the same heart rate.

If you're new to structured training, a simple starting plan is: 3 zone 2 sessions per week of 45–60 minutes, plus 1 session with zone 4 intervals. Resist the urge to push into zone 3 — it's the "grey zone" that's too hard for recovery and too easy for adaptation.