Heart Rate Zones Calculator

Zone	Heart rate	What it trains
Zone 1 — Very light (50–60%)	122–134 bpm	Warm-up, recovery, active daily movement
Zone 2 — Light (60–70%)	134–146 bpm	Base endurance, fat oxidation, long easy sessions
Zone 3 — Moderate (70–80%)	146–159 bpm	Aerobic conditioning, tempo work
Zone 4 — Hard (80–90%)	159–171 bpm	Threshold intervals, speed endurance
Zone 5 — Maximum (90–100%)	171–184 bpm	VO2 max intervals, short maximal efforts

Method	Karvonen (heart-rate reserve)
Zones	Five, 50% to 100%
Inputs	Age, resting HR (optional)
Formulas	Tanaka, Fox, Nes

What is Heart Rate Zones Calculator?

Training zones divide your heart-rate range into bands, each targeting a different physiological adaptation. This calculator uses the Karvonen method, which works from heart-rate reserve — the gap between resting and maximum heart rate — rather than a flat percentage of maximum. That makes the zones personal: someone with a low resting heart rate gets wider, lower ranges than someone untrained. Zone 1 is easy recovery, zone 2 builds aerobic base, zone 3 is tempo, zone 4 is threshold and zone 5 is maximal. Most endurance training should sit in zones 1–2, with smaller amounts of work in 3–5. Optical wrist sensors can lag during intervals, so a chest strap is more reliable for zone work.

Common Uses for Heart Rate Zones Calculator

Set training zones for running or cycling
Keep easy sessions genuinely easy
Prescribe interval intensities
Track whether training is polarised correctly

Frequently Asked Questions

What is the Karvonen method?

It calculates target heart rate as ((max HR − resting HR) × intensity %) + resting HR. Because it uses heart-rate reserve, it produces more personal zones than simply taking percentages of max HR.

What is zone 2 training?

Zone 2 is roughly 60–70% of heart-rate reserve — a pace at which you can still hold a conversation. It builds aerobic base and fat oxidation and should make up most of an endurance plan's volume.

Why does my zone feel too easy?

Easy is the point. Zone 2 is meant to feel comfortable; the adaptation comes from volume, not intensity. Most people train their easy days too hard and hard days too easy — the opposite of what works.

Should I use max HR or heart-rate reserve?

Heart-rate reserve (Karvonen) is generally better when you know your resting heart rate, because it accounts for fitness. Percentage-of-max is simpler but less personal.