How this calculator works
The Mifflin–St Jeor equation estimates resting energy expenditure. Maintenance multiplies it by a conventional activity factor, from 1.2 to 1.9; these broad factors add uncertainty and are not a personal measurement. This tool uses the study’s 19–78 adult age range and is not intended for pregnancy, childhood or clinical nutrition planning.
The formula
Resting kcal/day = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + S
S = +5 for the male equation, −161 for the female equation
Maintenance = resting energy × chosen activity factor.A quick example
For the male equation at age 30, 80 kg and 180 cm: resting energy is 800 + 1,125 − 150 + 5 = 1,780 kcal/day. At factor 1.2, estimated maintenance is 2,136 kcal/day.
How to use this calculator
- Enter adult age and choose the equation’s sex coefficient.
- Enter height in cm and weight in kg.
- Choose a broad activity level and read the estimates with their limitations.
A few common questions
Is this a calorie target for weight loss?
No. It estimates resting and maintenance energy, without recommending a deficit or treatment.
What does BMR mean here?
The displayed BMR/REE value is a predicted resting energy expenditure, not a lab measurement of basal metabolism.
Why can real needs differ?
Body composition, health, activity patterns and the approximate activity factor can all affect actual expenditure.