Heart Rate Zone Calculator

Calculate your 5 heart rate training zones using the Karvonen formula with resting heart rate.

Last updated: April 2026 · Source: NHS — Physical activity guidelines for adults

Measure first thing in the morning

Max Heart Rate

190 BPM

Heart Rate Reserve

125 BPM

Zone 1 — Recovery

Active recovery, warm-up

128–140

Zone 2 — Aerobic

Fat burning, endurance base

140–153

Zone 3 — Tempo

Aerobic fitness improvement

153–165

Zone 4 — Threshold

Speed endurance, lactate threshold

165–178

Zone 5 — Maximum

Maximum effort, sprinting

178–190

Using Karvonen formula (heart rate reserve method) for more accurate zones.

Disclaimer

This calculator is provided for informational purposes only and should not be considered as financial or tax advice. All calculations are performed locally in your browser — no personal data is collected or sent to our servers. Rates and thresholds are sourced from HMRC and GOV.UK and are updated for the current tax year. Always verify results with HMRC or consult a qualified professional before making financial decisions.

How It Works

Heart rate training zones are calculated as percentages of your maximum heart rate (MHR). The simplest estimate of MHR is 220 minus your age. The calculator divides the range from resting heart rate to MHR into five zones: Zone 1 (50–60%, warm-up), Zone 2 (60–70%, fat burn), Zone 3 (70–80%, aerobic), Zone 4 (80–90%, threshold) and Zone 5 (90–100%, VO2 max).

For greater accuracy, the Karvonen method uses your resting heart rate to calculate a heart rate reserve (HRR = MHR − resting HR), then applies zone percentages to HRR and adds back the resting heart rate. This produces personalised zones that reflect your fitness level.

Zone 2 training is recommended for building an aerobic base and efficient fat oxidation. The NHS recommends at least 150 minutes of moderate-intensity activity per week (roughly Zone 2–3) or 75 minutes of vigorous activity (Zone 4–5). Enter your age and resting heart rate to see your personalised zones.

Example: Age 35, resting heart rate 65 bpm

  1. Estimated MHR: 220 − 35 = 185 bpm
  2. Heart rate reserve: 185 − 65 = 120 bpm
  3. Zone 2 (60–70%): 65 + (120 × 0.60) to 65 + (120 × 0.70) = 137–149 bpm
  4. Zone 4 (80–90%): 65 + (120 × 0.80) to 65 + (120 × 0.90) = 161–173 bpm

Source: NHS — Physical activity guidelines for adults

Frequently Asked Questions

What does the Heart Rate Zone Calculator do?
Calculate your 5 heart rate training zones using the Karvonen formula with resting heart rate. All calculations are performed in your browser using official UK rates and thresholds.
Is this medical advice?
No. This calculator is for informational purposes only and does not constitute medical advice. Always consult your GP or an appropriate healthcare professional for medical guidance.
Are the reference values from the NHS?
Where applicable, this calculator uses reference values and guidelines from the NHS and other UK health authorities. Individual needs may vary based on personal health circumstances.