Estimate the Energy Your Body Uses at Rest
Enter your age, body measurements, and sex used by the equation to estimate resting metabolic rate with the Mifflin–St Jeor formula.
What is resting metabolic rate?
Resting metabolic rate (RMR), also called resting energy expenditure, estimates how much energy your body uses while awake and resting. It supports essential functions such as breathing, circulation, temperature regulation, and organ activity.
RMR does not include all calories used during normal movement, structured exercise, or digestion. To estimate total daily energy expenditure, an activity adjustment must be applied separately.
Formula used
This calculator uses the Mifflin–St Jeor equation, a widely used prediction formula for resting energy expenditure in adults.
Male: RMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5
Female: RMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age − 161
The displayed range is 90% to 110% of the formula result. It illustrates ordinary prediction uncertainty; it is not a measured confidence interval and does not guarantee that an individual’s true RMR falls within it.
For clinical context, see the NCBI Endotext table on estimating RMR.
RMR versus BMR
| Measure | What it represents | Testing conditions |
|---|---|---|
| RMR | Energy used while awake and resting | Measured under controlled resting conditions, but generally less strict than BMR testing |
| BMR | Minimum energy required for essential body functions | Traditionally measured under stricter fasting, temperature, and rest conditions |
In everyday calorie planning, the terms are sometimes used interchangeably and prediction equations may produce the same numerical estimate. Laboratory indirect calorimetry is required to measure resting energy expenditure rather than predict it.
How to interpret your result
- The result is the estimated energy used at rest, not your full daily calorie requirement.
- Muscle mass, genetics, hormones, illness, medications, sleep, and recent dieting can affect actual resting energy use.
- Weight and height should be entered as current measurements for the most relevant estimate.
- For weight planning, combine RMR with daily activity and use your multi-week weight trend to refine the estimate.
Frequently asked questions
Is RMR the number of calories I should eat?
No. RMR covers resting energy only. Most adults require more energy because total daily needs also include movement, exercise, and the energy used to digest food.
Why does the calculator ask for sex?
The Mifflin–St Jeor equation uses different constants for male and female reference groups. Choose the option used for your physiological assessment; a clinician can advise when the standard equation is not appropriate.
Can my RMR change?
Yes. RMR can change with body weight, lean mass, age, health status, medication, and prolonged changes in calorie intake.
What is the most accurate way to know my RMR?
Indirect calorimetry performed under standardized conditions measures respiratory gases and is more individualized than a prediction equation.