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Heart Rate Zones

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Calculate your five training heart-rate zones from age and resting heart rate, using the Tanaka, Fox, or Karvonen methods — instant and fully in-browser.

5 Zones
Instant
100% Client-Side
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1. Enter your details

Enter your resting heart rate to use the more accurate Karvonen (heart-rate-reserve) method. Leave it blank to use a percentage of your maximum heart rate.

Informational only — not medical advice. These are estimates; consult a doctor before starting or changing a training programme, especially if you have a heart condition.

2. Your training zones

Max heart rate
187 bpm
Method
% of max HR
Zone 1 — Recovery
94–112 bpm
Very light. Warm-up, cool-down, active recovery.50–60%
Zone 2 — Aerobic / Fat Burn
112–131 bpm
Light, sustainable. Builds endurance and burns fat.60–70%
Zone 3 — Aerobic
131–150 bpm
Moderate. Improves aerobic capacity and efficiency.70–80%
Zone 4 — Threshold
150–168 bpm
Hard. Raises lactate threshold and speed.80–90%
Zone 5 — Maximum
168–187 bpm
Maximal effort. Short intervals only.90–100%

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How to Use

  1. 1 Enter your age
  2. 2 Optionally add your resting heart rate for the Karvonen method
  3. 3 Pick a max-HR formula: Tanaka, Fox, or a measured value
  4. 4 Read your maximum heart rate and five zones
  5. 5 Use the bpm ranges to guide each workout's intensity

Features

  • Five training zones from recovery to maximum effort
  • Tanaka (208 − 0.7 × age) and Fox (220 − age) formulas
  • Karvonen heart-rate-reserve method when you add resting HR
  • Custom maximum heart rate for lab-measured values
  • Clear beats-per-minute ranges and intensity percentages
  • Runs entirely in your browser — nothing is uploaded

Why it Matters

Training by feel alone often means going too hard on easy days and not hard enough on hard days. Heart-rate zones turn intensity into a number you can target, so easy runs stay easy and intervals hit the right effort. Knowing your zones makes a training plan measurable instead of guesswork.

★★★★★

Use Cases

Endurance Training

Keep easy sessions in Zone 2 to build an aerobic base

Interval Workouts

Target Zone 4–5 ranges for threshold and VO2 efforts

Fat-Burn Sessions

Find the moderate zone for steady, sustainable effort

Recovery Days

Stay in Zone 1 so easy days actually aid recovery

What this tool does

The Heart Rate Zones calculator estimates your maximum heart rate and the five training zones — from recovery to maximum effort — as beats-per-minute ranges. Add your resting heart rate to switch to the more personal Karvonen method.

How it works

It estimates HRmax with the Tanaka, Fox, or a custom value, then derives each zone either as a percentage of HRmax or, when resting HR is supplied, with the Karvonen heart-rate-reserve formula. The logic is a pure function and runs fully offline.

Informational only — not medical advice

These zones are estimates from population formulas and are for general fitness information only. They are not medical advice. Consult a doctor before starting or changing a training programme, especially if you have a heart condition, take medication that affects heart rate, or feel unwell during exercise.

Privacy

Everything runs locally in your browser. No values are uploaded, logged, or stored.

Frequently Asked Questions

How are heart-rate zones calculated?
First the tool estimates your maximum heart rate (HRmax). Without a resting heart rate, each zone is a percentage of HRmax. With a resting heart rate, it uses the Karvonen method on your heart-rate reserve (HRmax minus resting), which personalises the ranges and is generally more accurate.
Which max-heart-rate formula should I use?
Tanaka (208 − 0.7 × age) is more accurate across ages and is the default. Fox (220 − age) is the classic, simpler estimate. If you've had your true maximum measured in a lab or a max test, choose Custom and enter that value for the best precision.
What do the five zones mean?
Zone 1 (50–60%) is recovery, Zone 2 (60–70%) is easy aerobic and fat-burning, Zone 3 (70–80%) builds aerobic fitness, Zone 4 (80–90%) is threshold work, and Zone 5 (90–100%) is maximal effort for short intervals only.
Are these numbers exact?
No — they're estimates from population formulas. Your true maximum and zone responses vary with genetics, fitness, medication, heat, and fatigue. Use the ranges as a guide and adjust based on how you feel and on a professional assessment.
Is my data stored anywhere?
No. The calculation runs entirely in your browser. Nothing you enter is uploaded, logged, or stored — refreshing the page clears everything.
📖

Want to understand the math?

Browse all guides →
Heart Rate Zones Explained
heart rate zones

Heart Rate Zones Explained: Max HR, Karvonen and Training

A clear guide to heart-rate training zones — how to estimate your maximum heart rate, what the five zones mean, the Karvonen method, and how to train by them.

23 Jun 2026

5 min read

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