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Heart Rate Zone Calculator

Calculate personalised heart rate training zones using the Karvonen method. Find your fat burn and aerobic zones.

Last reviewed: 5 September 2025Source: NHS — Health A-Z
Heart Rate Zone Calculator · IEHealth & Fitness

Rates & sources

Population-average body composition metrics. Always consult a qualified clinician before making health decisions.

Source: NHS — Health A-Z — figures refreshed at the start of each tax year.

When to use this calculator

  • Before setting a new health goal or checking whether a plan is realistic.
  • When you want to compare different assumptions without tracking them manually.
  • When you need a quick baseline before discussing the result with a professional.

A realistic Ireland planning example

Use these sample inputs as a quick scenario test, then change one variable at a time to compare outcomes.

Age

35

Resting Heart Rate (bpm)

5%

After entering these figures, compare max hr, fat burn and aerobic before deciding which scenario looks strongest.

How to read your results

Max HR

Use this metric to compare scenarios side by side and understand how the key drivers affect the final outcome.

Fat Burn

Use this metric to compare scenarios side by side and understand how the key drivers affect the final outcome.

Aerobic

Use this metric to compare scenarios side by side and understand how the key drivers affect the final outcome.

Threshold

Use this metric to compare scenarios side by side and understand how the key drivers affect the final outcome.

VO2 Max

Use this metric to compare scenarios side by side and understand how the key drivers affect the final outcome.

Method & assumptionsAuthoritative sources

Enter your age and resting heart rate to calculate personalised heart rate training zones using the Karvonen method. Zone 1 (50–60% heart rate reserve) is gentle recovery; Zone 2 (60–70%) builds aerobic base and fat burning; Zone 3 (70–80%) improves aerobic capacity; Zone 4 (80–90%) builds lactate threshold. Most training plans recommend spending 80% of running time in Zones 1–2.

Common mistakes

  • !Using optimistic assumptions without testing a more cautious scenario as well.
  • !Comparing outputs from different tools without checking that the inputs match.
  • !Treating the result as a final quote instead of a planning estimate.

What to do next

  • Try at least one more scenario so you can compare a realistic range instead of a single estimate.
  • Use the related calculators below to cross-check the decision from another angle.
  • Open one of the linked guides if you need more context before you act on the result.

Frequently asked

The 220-minus-age formula gives a rough estimate. A more accurate method is a maximal effort test (e.g. running uphill to exhaustion) under professional supervision.

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