Metabolic Age Calculator for Women

This calculator computes your BMR with the Mifflin-St Jeor equation and compares it with a reference woman of median US height and weight at every age, plus a small adjustment for training (active women hold more muscle than the sedentary average).

BMR (Mifflin-St Jeor, women): BMR = 10 x weight(kg) + 6.25 x height(cm) - 5 x age - 161 (Mifflin MD et al.)

Metabolic age: The age at which the median US woman's BMR equals yours (+/- lifestyle adjustment) (NHANES anthropometric reference data)

There is no clinical standard for metabolic age; smart scales and calculators (including this one) estimate it by comparing your BMR to population averages. It is best used as a motivating snapshot, not a diagnosis. What it CAN show: whether your body composition and size put your calorie burn above or below women your age.

The honest limitation: two women with the same weight can have very different muscle mass, and muscle is what really drives BMR. A smart scale with bioimpedance guesses at that; our formula uses a lifestyle adjustment instead and tells you so.

BMR rises with lean mass, so the levers are: resistance training 2 to 3 times per week, enough protein (1.2 to 1.6 g per kg per day), and losing fat SLOWLY enough to keep muscle. Crash dieting lowers BMR and raises metabolic age, the exact opposite of the goal.

Expect movement in months, not days. A realistic win is shaving 2 to 5 years over 6 months of consistent strength work with adequate protein.

At or below your calendar age. Within 2 years either way is normal calibration noise. More than 5 years above your age suggests low lean mass for your size; more than 5 below usually reflects consistent training.

It is an educational estimate, not a validated clinical metric. The BMR math underneath (Mifflin-St Jeor) is well validated; the 'age' framing is a comparison to population averages. Treat it as a progress compass, not a lab result.

Usually because weight is high relative to lean mass: BMR per pound is lower when a larger share of weight is fat. It moves in the right direction with strength training, protein and gradual fat loss.

Yes. Postmenopausal women in resistance-training studies consistently gain lean mass and raise resting metabolic rate. The response is slower than at 30, but the direction is fully available at any age.