You need a resting-calorie estimate as the first step toward a TDEE or daily calorie calculation.
BMR Calculator
Estimate basal metabolic rate with the Mifflin-St Jeor formula locally in your browser.
Start here
Choose sex and US customary or metric units.
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Your body measurements are calculated locally in your browser and are not uploaded to a server.
Useful for
Estimate resting calorie needs
Measurement units
BMR1,239 kcal
Estimated calories your body uses at rest for basic functions.
Per kg of body weight22.5 kcal
Use this as the starting point for estimating TDEE and daily calorie targets.
FormulaMifflin-St Jeor
Mifflin-St Jeor is commonly used as a starting estimate for adults.
BMR is an estimate. Real metabolism can vary with muscle mass, health status, sleep, hormones, and other factors.
Quick answer
Estimate basal metabolic rate with Mifflin-St Jeor
Enter age, sex, height, and weight to estimate the calories an adult body would use at rest over a day. US customary and metric inputs are supported.
BMR is not total daily calorie need and can differ from a measured resting metabolic rate or an individual's actual metabolism.
TDEE Calculator: Estimate total daily energy expenditure from BMR and activity level locally in your browser.
About this tool
Estimate basal metabolic rate with the Mifflin-St Jeor formula locally in your browser.
Your body measurements are calculated locally in your browser and are not uploaded to a server.
Health information notice
BMR is a formula estimate and does not replace medical, nutrition, or metabolic testing. Health conditions, medication, pregnancy, age, muscle mass, and training status can change real energy needs.
How to use it
- Choose sex and US customary or metric units.
- Enter age, height, and weight.
- Review estimated BMR, the worked example, and formula limitations.
Common use cases
- Estimate resting calorie needs
- Use BMR as the base for TDEE
- Start daily calorie planning with a formula estimate
How BMR Is Estimated
This calculator uses the Mifflin-St Jeor equation. It estimates resting energy needs from sex, age, height, and weight, then can be used as the base for TDEE.
| Input | Why it matters | Reminder |
|---|---|---|
| Sex | The formula uses different constants for male and female settings | This is a formula field, not a complete picture of physiology. |
| Age | Estimated resting needs usually decrease with age | Real metabolism varies by person. |
| Height and weight | Used to estimate body size and resting energy | Muscle mass is not directly measured. |
Worked BMR Example
For a 30-year-old female setting who is 5 ft 5 in and 140 lb, the tool converts the measurements to about 165.1 cm and 63.5 kg. The Mifflin-St Jeor estimate is about 1,356 kcal per day at rest.
That number is not a suggested food intake. It is the resting estimate used as the starting point for a TDEE calculation.
| Input | Example | How it enters the formula |
|---|---|---|
| Weight | 140 lb (about 63.5 kg) | 10 x weight in kg |
| Height | 5 ft 5 in (about 165.1 cm) | 6.25 x height in cm |
| Age | 30 | Subtract 5 x age |
| Female formula constant | -161 | Produces an estimate near 1,356 kcal/day |
BMR Versus the Number You Usually Need
| Question | Start with | Next step |
|---|---|---|
| How much energy might my body use at rest? | BMR | Read the formula limits. |
| What might maintain my weight during normal life? | TDEE | Choose a conservative activity level. |
| What calorie target matches a goal? | Daily Calorie Goal | Start from TDEE and monitor real trends. |
| Do I need a clinical measurement? | Neither calculator | Discuss indirect calorimetry or personal needs with a qualified professional. |
FAQ
Which formula is used?
This calculator uses the Mifflin-St Jeor equation, a common adult resting energy estimate.
Is BMR the same as daily calories?
No. BMR estimates resting needs. TDEE adds activity on top of BMR.
Are my inputs uploaded?
No. The calculation runs locally in your browser.