Reference formulas and worked examples below keep their stated units. Monetary examples use USD; dimensional examples use US customary units unless labeled otherwise. Metric calculator inputs are converted to these reference units before calculation. Choosing another currency does not convert example amounts or exchange money.
How to use this bmr calculator
This BMR calculator uses the Mifflin–St Jeor resting energy expenditure equation. It estimates resting calories; everyday movement and exercise are added separately in the TDEE calculator.
How the calculation works
Resting kcal/day = 10 × weight in kg + 6.25 × height in cm − 5 × age in years + the selected coefficient. The male coefficient is +5; the female coefficient is −161.
Kilojoules/day = kcal/day × 4.184. The hourly figure is the daily estimate divided by 24, not an estimate of the energy cost of a specific activity.
Worked example
For the male coefficient, 70 kg, 175 cm and age 30: 10 × 70 + 6.25 × 175 − 5 × 30 + 5 = 1,648.75 kcal/day at rest. Using the female coefficient with the same measurements gives 1,482.75 kcal/day.
Limits and assumptions
An estimate from adult measurements, not a measured metabolic rate or a diagnosis. This model does not adjust for pregnancy, breastfeeding, illness, unusual body composition or athletic training. The source equation studied adults aged 19–78; this tool keeps that age range. It is not a calorie restriction or weight-loss prescription.
Frequently asked questions
Is this the same as my daily calorie use?
No. This is the resting component. Daily movement and exercise raise total energy expenditure; TDEE applies an activity assumption.
Why choose an equation coefficient?
The published model has two sex-specific constants. Select the coefficient relevant to the scenario; the model does not measure your individual physiology.
What age range does this tool support?
Whole ages 19–78, matching the source study’s age range. A different model is needed outside the scope used here.
Can I use the result as a diet target?
The resting estimate is not a recommended food intake. It excludes activity and individual medical or nutritional needs.
References
Mifflin et al.: predicting resting energy expenditure (1990)