Metabolic Age Calculator

What is metabolic age?

This metabolic age calculator estimates your body fat percentage, then compares it to the average body fat % for your gender at different ages. Whichever age matches your estimated body fat % becomes your metabolic age. A metabolic age lower than your actual age suggests a leaner-than-average body composition for your age; a higher one suggests the opposite.

How your body fat % is determined

• If you enter a body fat % (between 3% and 70%), that value is used directly, and your BMR is calculated with the Katch-McArdle formula, which uses lean body mass instead of total weight.
• If you don't enter a body fat %, it's estimated from your BMI, age, and gender using the Deurenberg formula, and your BMR is calculated with the Mifflin-St Jeor formula instead.

Providing your actual body fat % (from a scale, caliper, or DEXA scan) gives a more accurate metabolic age than the BMI-based estimate.

BMR vs. TDEE

BMR (Basal Metabolic Rate) is the energy your body needs just to stay alive at rest. TDEE (Total Daily Energy Expenditure) is your BMR adjusted for how active you are day to day, using an activity multiplier from sedentary (little or no exercise) up to extra active (very intense daily training or a physical job).

What the result includes

• Your basal metabolic rate (BMR) in calories per day
• Your total daily energy expenditure (TDEE) based on your activity level
• Your body fat % (entered or estimated) used in the calculation
• Your metabolic age and how it compares to your actual age

Is a metabolic age calculator accurate?

Metabolic age is an estimate, not a medical or clinical measurement. When you don't provide a body fat %, it's approximated from BMI using the Deurenberg formula, which doesn't distinguish muscle from fat — a very muscular person can be estimated as having a higher metabolic age than they actually do. This calculator accepts ages from 15 to 80; use it as a general wellness indicator, not a diagnosis.