Katch-McArdle Calculator for Women

Unlike Mifflin-St Jeor or Harris-Benedict, which carry a separate constant for each sex, Katch-McArdle has no sex term at all — it runs entirely off lean mass. That does not mean it ignores the difference between men and women; it means the difference is already baked into the input. Because women on average carry a higher proportion of essential fat, the same scale weight usually converts to a little less lean mass, and the formula returns a correspondingly lower BMR without needing a sex adjustment. Work an example: a woman at 65 kg and 25% body fat has 48.75 kg of lean mass, so her BMR is 370 + 21.6 × 48.75 ≈ 1,423 kcal, and at a moderate activity factor of 1.55 her maintenance is about 2,206 kcal a day.

Since your body fat percentage is the one input that matters most, it helps to know where a figure sits. The commonly cited ACE ranges for women read as a band, not a scorecard: about 14–20% is athletic, 21–24% fitness, 25–31% average, and 32% and above above-average, with 10–13% counted as essential fat — the minimum the body needs to function. These are descriptions of what is commonly measured, not targets. If you don't have a number yet, the Body Fat % Calculator will estimate one you can bring back here.

The reason lifters and recompositioners favour a lean-mass formula applies just as much to women: it lets you plan around the tissue you want to keep. Set protein off lean mass to protect muscle in a deficit, and judge progress on the fat-mass trend rather than scale weight, which can barely move while composition shifts underneath it. Turn your maintenance figure into a moderate plan with the Calorie Deficit Calculator, then split those calories into protein, carbs and fat with the Macro Calculator. Because lean mass and maintenance both change as you progress, re-run the numbers every few kilograms.