BMR calculator: estimate basal metabolic rate and TDEE
BMR is the energy your body uses at complete rest. Using the Mifflin-St Jeor equation, a 30-year-old man who is 5 ft 9 in and 165 lb has a BMR of about 1,700 kcal a day; multiplying BMR by an activity factor of 1.2–1.9 estimates your total daily energy expenditure (TDEE). Enter US or metric units below.
Calculate your basal metabolic rate (BMR)
What is BMR (basal metabolic rate)?
Basal metabolic rate is the energy your body is estimated to use at complete rest for essential functions. It covers processes such as breathing, circulation, cellular activity and temperature regulation. It does not include walking, work, exercise or digestion.
BMR is a useful starting point, but it is not a recommended calorie intake. Total daily energy expenditure is the more relevant estimate for everyday planning. Strictly, the Mifflin-St Jeor equation predicts resting energy expenditure (REE). BMR uses more restrictive measurement conditions; online calculators commonly use the BMR label for this resting estimate.
How is BMR calculated? The Mifflin-St Jeor formula
The equation uses weight in kilograms (W), height in centimeters (H) and age in years (A). US-unit inputs are converted before calculation. For example, 165 lb is 74.8 kg and 5 ft 9 in is 175.3 cm, so a 30-year-old man gets 748.4 + 1,095.4 − 150 + 5 ≈ 1,699 kcal a day.
| Equation input | Formula |
|---|---|
| Male | 10W + 6.25H − 5A + 5 |
| Female | 10W + 6.25H − 5A − 161 |
What is the difference between BMR and TDEE?
TDEE estimates the energy you use across an ordinary day, including walking, work and exercise. The calculator multiplies BMR by one of the activity factors below, but short labels cannot capture every job, training schedule or movement pattern. Treat the values as a range to test against real weight and intake trends.
| Activity level | Multiplier |
|---|---|
| Sedentary | 1.20 |
| Light activity | 1.375 |
| Moderate activity | 1.55 |
| Very active | 1.725 |
| Extra active | 1.90 |
Why your actual energy use may differ
Equations estimate the average relationship between age, height, weight and resting energy use. They do not directly measure muscle mass, hormones, illness, medication, pregnancy, adaptive changes or spontaneous daily movement.
- Use the result as a starting range, not an exact daily allowance.
- Compare the estimate with several weeks of consistent intake and weight data.
- Recalculate after a meaningful change in body weight or activity.
- Seek individualized advice when health conditions, pregnancy or eating-disorder risk affect energy planning.
Use your estimate in context
Resting energy is one part of your daily needs. Explore the next calculation or keep a record of meals before drawing conclusions.
Sources
Nutrition values are estimates based on authoritative food-composition data and public-health guidance. Product labels and serving sizes vary.
- Mifflin-St Jeor resting energy equation
Original peer-reviewed study describing the equation used by this calculator.
- NIDDK Body Weight Planner
US National Institute of Diabetes and Digestive and Kidney Diseases tool and guidance for weight and energy planning.
- Dietary Guidelines for Americans
US government evidence-based guidance on energy balance and healthy dietary patterns.
Frequently asked questions
- What is BMR?
- BMR (basal metabolic rate) is the estimated energy your body uses at complete rest to keep essential functions running, such as breathing, circulation and temperature regulation. It is the largest part of daily energy use: about 1,700 kcal a day for a 30-year-old man who is 5 ft 9 in and 165 lb.
- How do you calculate BMR?
- This calculator uses the Mifflin-St Jeor equation with weight in kilograms (W), height in centimeters (H) and age in years (A): BMR = 10W + 6.25H − 5A + 5 for men and 10W + 6.25H − 5A − 161 for women. Pounds, feet and inches are converted to metric before the equation is applied.
- What is the difference between BMR and TDEE?
- BMR estimates the energy you use at complete rest, while TDEE (total daily energy expenditure) estimates everything you burn in a day, including walking, work and exercise. TDEE is calculated by multiplying BMR by an activity factor, from 1.2 for a sedentary person to 1.9 for someone who is extra active.
- How accurate is a BMR calculator?
- A BMR calculator gives a population-based estimate, not a measurement. Body composition, health conditions, medication, environment and actual activity can make your real energy use higher or lower than the equation predicts, so treat the result as a starting point and adjust it against several weeks of weight and intake data.
- Should I eat fewer calories than my BMR?
- BMR alone cannot establish a safe calorie intake. It estimates resting energy use; it is not a universal intake floor or a daily calorie target. Consider total daily expenditure, nutritional adequacy and personal circumstances. Get individual advice for weight-loss planning, medical needs, pregnancy or eating-disorder recovery.
- Does the calculator support pounds and feet?
- Yes. Choose US units to enter pounds, feet and inches, or metric for kilograms and centimeters. The calculator converts US-unit inputs to metric and then applies the same Mifflin-St Jeor equation, so both options give the same result.