Metabolic Age Calculator

Work out metabolic age instantly with clear inputs, formula shown and shareable results.

About Metabolic Age Calculator

Solves the Mifflin-St Jeor equation for age, giving the age at which your body size would be predicted to have the measured basal metabolic rate.

Formula

Mifflin-St Jeor inverted

BMR = 10 x weight + 6.25 x height - 5 x age + 5 (men) or -161 (women); rearranged, age = (10 x weight + 6.25 x height + constant - BMR) / 5

Worked example

With the default values below, Metabolic Age Calculator returns Metabolic age of 59.8. Change any input above and every figure here is recalculated in your browser.

Inputs used

Measured or estimated BMRaccepts 700–4,000 kcal/day: 1,500 kcal/day
Weightaccepts 30–250 kg: 70 kg
Heightaccepts 120–220 cm: 175 cm
Sexone of Male, Female: Male

Results

Metabolic age: 59.8 years
Predicted BMR at age 40 for this body size: 1,599 kcal/day
BMR per kilogram: 21.43 kcal/kg/day
Interpretation: Metabolic rate consistent with this age on the Mifflin-St Jeor equation

Step by step

1Values used
2Mifflin-St Jeor inverted
3Metabolic age= 59.8 years
4Predicted BMR at age 40 for this body size= 1,599 kcal/day
5BMR per kilogram= 21.43 kcal/kg/day
6Interpretation= Metabolic rate consistent with this age on the Mifflin-St Jeor equation

Assumptions and limits

The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
Educational estimate only. Not a substitute for professional clinical judgement, and must not be used to make treatment or dosing decisions.
This is an estimate for general information and not professional medical advice. See the full disclaimer for the limits that apply to this kind of calculator.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Educational estimate only. Not a substitute for professional clinical judgement, and must not be used to make treatment or dosing decisions.

Frequently Asked Questions

What does metabolic age really measure?

Mostly lean mass relative to body size; a higher muscle mass raises BMR and lowers the calculated age.

Is it a health assessment?

No. It is a rearrangement of a prediction equation, useful for motivation rather than diagnosis.