How to use it
Enter your details
Choose your sex and type in your age, weight in kilograms and height in centimetres.
Pick an activity level
Select how active a typical week is. This multiplies your resting burn into a daily total.
Read your targets
See your BMR and TDEE, plus calorie targets to lose, maintain or gain weight.
About the Mifflin-St Jeor formula
Your Basal Metabolic Rate (BMR) is the energy you burn at rest. This tool uses the Mifflin-St Jeor equation, widely regarded as one of the most accurate for everyday use: BMR = 10·kg + 6.25·cm − 5·age + 5 for men, and the same minus 161 for women. Your TDEE is that BMR multiplied by an activity factor. The lose and gain targets shift the maintenance figure by 500 kcal/day, roughly a half-kilo per week. This is for general guidance, not medical advice — check with a professional before making big changes to your diet.
Questions
Is anything uploaded?
No. The calculation runs entirely in your browser and nothing you type is sent anywhere or stored.
Why 500 calories for the targets?
A deficit or surplus of about 500 kcal/day works out to roughly 0.45 kg (1 lb) of change per week, a sustainable pace for most people.
How accurate is this?
It is a solid estimate. Real energy needs vary with body composition, genetics and day-to-day activity, so treat it as a starting point and adjust by results.