Content reviewed: 24 September 2026
How the daily calorie estimate is produced
This tool first estimates resting energy needs with the Mifflin–St Jeor equation, then multiplies that result by the activity factor you select. The output is an estimate of daily energy expenditure for an adult.
Inputs that affect the estimate
The equation uses age, body weight, height and the sex-specific constant built into the formula. The activity selection then scales the resting estimate to approximate total daily needs.
Why your real requirement can differ
Activity categories are broad, and individual energy expenditure varies with body composition, training volume, occupation, health, pregnancy, medications and many other factors. Food labels and tracking methods also contain measurement error.
Use it as a starting point
A calculator can provide a planning estimate, but long-term changes in body weight, performance, hunger and health are better feedback than treating one calorie number as exact. For medical nutrition needs, eating disorders, pregnancy or significant health concerns, seek personalised professional advice.
Read BMI and Calorie Estimates for the limitations of both tools.