Target Heart Rate Calculator

Target heart rate is the single-number version of Karvonen.

Instead of asking “what are all five zones?”, it asks:

What BPM matches this one intensity?

Formula

target = RHR + intensity x (HRmax - RHR)

Where:

• RHR is resting heart rate
• HRmax is maximum heart rate
• HRmax - RHR is heart rate reserve
• intensity is a decimal, like 0.70

Zonas truncates the result to whole BPM.

Example

Use the default calculator example:

Input	Value
Age	30
Estimated HRmax	187
Resting HR	60
Intensity	70% HRR

The reserve is:

187 - 60 = 127

The target is:

60 + trunc(0.70 x 127) = 148 BPM

That 148 BPM value is also the lower edge of Zone 3 in the flagship zone calculator example.

Why Resting Heart Rate Matters

Percent of max heart rate ignores the difference between rest and max.

Karvonen uses that difference directly.

For two people with the same HRmax, the person with the lower resting heart rate has a larger reserve. The same target intensity can land at a different BPM.

When To Use This Calculator

Use it when you want a single target:

• a steady aerobic target
• a warm-up ceiling
• an interval intensity
• a conservative cap for a return-to-training session

Use the full zone calculator when you want five ranges.

What It Does Not Know

It does not know your threshold, medication status, temperature, altitude, stress, or fatigue.

It is a calculator, not a coach.