Heart Rate Zone Calculator

Calculate your 5 heart rate training zones using the Fox formula and Karvonen method

Age

Resting Heart Rate (bpm) — Optional

Measured after waking up before getting out of bed

Fitness Goal

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Quick summary

This calculator uses the Fox formula (220 − age) to estimate your maximum heart rate, then calculates 5 training zones from Zone 1 (50–60% MHR, warm-up) to Zone 5 (90–100% MHR, maximum effort). If you enter your resting heart rate, the more accurate Karvonen method is also calculated.

Reviewed by Simple Calculators TeamLast reviewed July 10, 2026

For information only — not medical advice. Results are estimates from published formulas and can't account for your health history. Talk to a doctor or other qualified clinician before making health decisions.

How to use this calculator

Enter the inputs requested by the calculator.
Choose the units or options that match your situation and review the assumptions.
Run or update the calculation to see the result.
Review the result, breakdown, and formulas shown on the page.
Check the inputs, units, dates, and limitations before saving or sharing the result.

Heart Rate Formulas

Maximum Heart Rate (Fox Formula)

\text{MHR} = 220 - \text{age}

MHR: Maximum Heart Rate in bpm
age: Age in years

Worked example

35-year-old person

Given: age = 35
Calculation: $\text{MHR} = 220 - 35$
Result: MHR = 185 bpm

Karvonen Method (Target HR)

\text{THR} = \text{RHR} + (\text{MHR} - \text{RHR}) \times \%\text{intensity}

THR: Target Heart Rate
RHR: Resting Heart Rate
MHR: Maximum Heart Rate
%intensity: Desired intensity (e.g. 0.70 for 70%)

Worked example

MHR=185, RHR=60, Zone 3 lower bound (70%)

Given: MHR = 185
RHR = 60
intensity = 0.70
Calculation: $\text{THR} = 60 + (185 - 60) \times 0.70$
Result: THR = 147.5 bpm

Frequently asked questions

What is the difference between Fox and Karvonen?

The Fox formula calculates zones as percentages of your maximum heart rate. The Karvonen method uses your heart rate reserve (MHR minus resting HR), which accounts for cardiovascular fitness and produces a more personalized result.

Which zone is best for fat burning?

Zone 2 (60–70% MHR) is the traditional fat-burning zone where your body primarily burns fat as fuel. However, higher-intensity zones burn more total calories even though the fat percentage is lower.

How do I measure my resting heart rate?

Measure your pulse for 60 seconds immediately after waking up before getting out of bed. A typical resting heart rate is 60–80 bpm for healthy adults; athletes may have 40–60 bpm.

Key terms

Maximum Heart Rate (MHR): The highest heart rate achievable during maximum exertion.
Heart Rate Reserve (HRR): MHR minus resting heart rate — represents usable heart rate capacity.
Karvonen Method: A formula for calculating target heart rates that uses HRR for more personalized zones.

Methodology, sources & limitations

This page shows the formula, assumptions, and limitations used for this estimate. Rates, thresholds, and other time-sensitive inputs can change, so verify them against the relevant official source before relying on a result.

For our review approach and the primary sources we consult, see the methodology and source policy. If you spot an outdated figure or formula, please contact us with a correction.

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