Karvonen Heart Rate Reserve Calculator

Separate resting heart rate from maximum heart rate, calculate the reserve, and build a Karvonen target from your chosen percentage.

Calculation inputs

Separate the three inputs

1
Record a resting measurement
Use a rested, calm measurement rather than a post-exercise reading.
2
Identify the maximum source
Choose an age prediction or a reliable previously measured maximum.
3
Keep the percentage definition explicit
This page uses reserve; the comparison shows what the same number means as %HRmax.

Measurement and method sources are linked below. Illustrations explain the workflow; they do not supply measurement data.

Resting baseline and the available reserve

Calculation results

Karvonen target heart rate146.3 bpm65% of heart-rate reserve + resting

Heart-rate reserve125 bpm

Maximum predicted190 bpm

Resting HR65 bpm

Same % of HRR146.3 bpm

Same % of HRmax123.5 bpm

Method difference22.8 bpm

Step-by-step solution

Choose the formula
$Target = resting + (maximum − resting) × intensity/100$
Substitute your measurements
$65 + (190 − 65) × 65/100$
Calculate in order
$Reserve 125 × 0.65 = 81.3; add 65$
Write the result
$146.3 bpm$

Representative resting and comfortable exercise contexts — Representative illustration · no measured heart-rate data are taken from the image.

1
Establish the maximum source
220 − age = 190 bpm
2
Separate baseline and reserve
190 − 65 = 125 bpm
3
Apply the selected denominator
65 + (190 − 65) × 65/100 = 146.3 bpm

Adult educational tool. Heart-rate medicines, rhythm disorders and medical conditions can change interpretation. Use clinician-set limits when you have them.

Intensity percentages are calculation inputs, not a prescribed training plan. %HRR and %HRmax are different denominators; their numerical percentages are not interchangeable.

Measurements & calculation details

146.3 bpm

Quantity	Value
Maximum source	220 − age
Maximum HR	190 bpm
Resting HR	65 bpm
Reserve	125 bpm
Selected intensity	65%
Selected method	Heart-rate reserve
Calculated target	146.3 bpm

Try a worked example

Choose an example to load its measurements into the calculator. Each result uses the same calculation engine as your own inputs. Back to your calculation

Understand the calculation

Concept & meaning

Heart-rate reserve is maximum HR minus resting HR. The Karvonen target adds a selected fraction of this reserve back to the resting baseline. The diagram shows this construction without labeling a particular percentage as universally safe.

Formula & special cases

Target = resting + (maximum − resting) × intensity/100. A percentage of reserve has a different denominator from the same percentage of maximum HR. For example, resting 60 and maximum 190 at 60% reserve give 138 bpm; 60% of maximum alone gives 114 bpm.

Scope & limitations

The reliability of the target depends on both measurements and any maximum-prediction model. A low or high percentage here is only arithmetic. Medicines, disease and an individualized exercise plan can make general heart-rate guidance unsuitable.

Target = resting + (maximum − resting) × intensity/100

Result from your current inputs

Karvonen target heart rate: 146.3 bpm

Frequently asked questions

What is heart-rate reserve?

The difference between maximum and resting heart rate, expressed in bpm. It is not the same abbreviation as heart-rate recovery.

Why is resting heart rate added back?

The selected percentage applies to the range above resting. Adding the baseline locates the target within that range.

Is 65% HRR the same as 65% HRmax?

No. Their denominators differ, so the resulting bpm differs unless the limiting inputs make them coincide.

Can I enter a measured maximum?

Yes, choose that source and use an already established reliable value. Do not undertake an unsupervised maximal test for this page.

Show all questions (5 more)Show fewer questions

What does the Karvonen Heart Rate Reserve calculate?

Separate resting heart rate from maximum heart rate, calculate the reserve, and build a Karvonen target from your chosen percentage.

Which values should I enter?

Use the labeled fields above. Values outside the supported range clear the result and show an explanation.

What formula does this calculator use?

Reserve: HRmax − HRrest; Chosen fraction: Reserve × p/100; Target: HRrest + chosen fraction

Why might my result differ from another source?

Results can differ because measurement methods, rounding and assumptions vary. This calculator is an estimate and is not a medical diagnosis.

Does the result update automatically?

Yes. Inputs and presets update the result, teaching diagram and expandable steps together. Invalid input clears the previous result.

Follow the baseline through the calculation

Calculation	Formula	Interpretation
Reserve	HRmax − HRrest	Difference in bpm
Chosen fraction	Reserve × p/100	Increment above resting
Target	HRrest + chosen fraction	No exercise prescription implied

Sources & References

ASPC clinical practice statement · 2022Reserve-based versus maximum-based exercise intensityRead the reference

American Heart AssociationGeneral maximum and target-rate contextRead the reference

References document the methods and their limitations; links and logos do not imply institutional endorsement or expert review.