Estimate the calories your body uses each day using the Mifflin-St Jeor equation. Enter your details to see a maintenance figure to work from. Nothing is stored.

To maintain your weight

1900 calories / day

An estimate of the energy your body uses at this activity level.

To lose weight gradually, many aim for roughly 500 fewer; to build, a small surplus.

This uses the Mifflin-St Jeor equation, a well-established estimate. Real needs vary with genetics, muscle and health, so treat it as a starting point, not a strict rule. It is not suitable during pregnancy or breastfeeding. See our protein and fibre guides for eating well. This tool is information, not medical advice.

How it works

Enter your details and activity level to estimate the calories your body uses in a day.

The formula and sources

It uses the Mifflin-St Jeor equation for women to estimate your resting metabolic rate, then multiplies by an activity factor to give a maintenance figure to work from.

Assumptions

You are a generally healthy adult.
Activity is estimated honestly.

Limitations

This is an estimate. Individual metabolism, muscle mass, and medical conditions shift the real number, so use it as a starting point and adjust to how your weight actually responds.

When to see a doctor

If you are managing a health condition, or have a history of disordered eating, work with your doctor or a dietitian rather than a calculator.

Primary sources

Mifflin MD, St Jeor ST, et al. American Journal of Clinical Nutrition, 1990. The paper that published the equation this tool uses. For women it is 10 times weight in kg, plus 6.25 times height in cm, minus 5 times age in years, minus 161. It was derived and validated in 498 healthy adults aged 19 to 78, 247 of them women, and included people with and without obesity.

Calculator version 1.0, Mifflin-St Jeor. Figures and formula last checked 27 July 2026 against the sources above. This tool gives general information and does not replace advice from your own doctor.

Frequently asked questions

How accurate is a calorie calculator?

It gives a solid estimate, usually within a few hundred calories. Metabolism, muscle mass and activity vary, so use the number as a starting point and adjust to how your weight responds.

What is the difference between BMR and TDEE?

BMR is the energy your body uses at rest. TDEE is your BMR plus everything you do in a day, which is the maintenance figure most people want.

How many calories should I eat to lose weight?

A deficit of about 500 calories a day below your maintenance figure is a common, gradual approach. Very low intakes are hard to sustain and often backfire.

Why am I not losing weight in a deficit?

Estimates can be off, day-to-day activity varies, and intake is easy to undercount. Track for a couple of weeks and adjust. See our guide to weight loss.

Calorie Calculator for Women (BMR & TDEE)