BMR Calculator for Women

The Mifflin-St Jeor equation does not use a different formula for women — it uses the same one, with a single term swapped. Everyone gets the same calories added for each kilogram of weight and centimetre of height, and the same small amount subtracted for each year of age. Then comes the sex term: men get +5, women get −161. That 166-calorie difference is the equation’s shorthand for a population average in body composition — for a given height and weight, women tend to carry proportionally more fat and less lean muscle, and because muscle burns more at rest, the formula nudges the resting estimate down to match. It is biological-sex arithmetic, plain and simple, and it is the only thing that changes when you select female. None of this is a verdict on any individual woman: a strength athlete carrying a lot of muscle can easily out-burn the average, which is exactly what the body-fat-based Katch-McArdle option captures if you have your number.

The figure this page returns is your resting burn — the energy your body spends keeping you alive while you do nothing. It is a baseline, not a meal plan, and the most common mistake is to read it as the number to eat. Doing that would leave most women under-fuelled, because a real day adds a great deal on top: every step, every task, every workout, even digesting food. The resting figure is simply the floor your daily budget is built on, and its value is that it makes the next step — adding activity — meaningful. Treat it as the starting line rather than the finishing one.

One honest caveat: special situations such as the menstrual cycle, pregnancy or breastfeeding shift a woman’s energy needs in ways that sit beyond any simple equation — they are a question for your own doctor or a registered dietitian, not a calculator. This tool estimates a general resting figure and does not try to model them.