Calculate your BMR and total daily calorie needs (TDEE) with the Mifflin-St Jeor equation using your sex, age, height, and weight.
Mifflin St Jeor Formula
The Mifflin-St Jeor equation estimates your basal metabolic rate (BMR), the number of calories your body burns at complete rest. It uses a different constant for males and females.
BMR (male) = 10*W + 6.25*H - 5*A + 5
BMR (female) = 10*W + 6.25*H - 5*A - 161
To estimate total daily energy expenditure (TDEE), the calories you burn in a full day including activity, multiply your BMR by an activity factor.
TDEE = BMR * activity factor
- W = body weight in kilograms (kg)
- H = height in centimeters (cm)
- A = age in years
- activity factor = a multiplier from 1.2 (sedentary) to 1.9 (extra active)
The weight, height, and age terms scale your resting calorie burn to your body size. Larger and younger people have higher BMR values, which is why weight and height add to the result while age subtracts from it. The sex constant (+5 for males, -161 for females) adjusts for the average difference in lean body mass. The activity factor then converts resting calories into a realistic daily total based on how much you move.
If you enter US units, the calculator converts pounds to kilograms (1 lb = 0.4536 kg) and feet and inches to centimeters (1 in = 2.54 cm) before applying the formula. In weight mode, the calculator reverses the math: it takes your target calories, divides by your activity factor to find the required BMR, and solves the equation for the body weight that produces it.
Activity Multipliers and Calorie Targets
The activity factor you choose has a large effect on your TDEE. Pick the level that matches a normal week, not your best week.
| Activity level | Description | Factor |
|---|---|---|
| Sedentary | Little or no exercise, desk job | 1.2 |
| Lightly active | Light exercise 1-3 days/week | 1.375 |
| Moderately active | Moderate exercise 3-5 days/week | 1.55 |
| Very active | Hard exercise 6-7 days/week | 1.725 |
| Extra active | Physical job or twice-daily training | 1.9 |
Once you know your TDEE, you can set a calorie goal based on your aim. These adjustments are common starting points.
| Goal | Daily calories | Expected change |
|---|---|---|
| Lose weight | TDEE minus 500 | About 1 lb per week |
| Maintain weight | TDEE | Stable weight |
| Gain weight | TDEE plus 300 to 500 | About 0.5 to 1 lb per week |
Example Problems
Example 1. A 30-year-old male weighs 80 kg and is 180 cm tall, with a moderately active lifestyle.
BMR = 10(80) + 6.25(180) - 5(30) + 5 = 800 + 1125 - 150 + 5 = 1780 calories per day.
TDEE = 1780 * 1.55 = 2759 calories per day.
Example 2. A 25-year-old female weighs 60 kg and is 165 cm tall, with a lightly active lifestyle.
BMR = 10(60) + 6.25(165) - 5(25) - 161 = 600 + 1031.25 - 125 - 161 = 1345.25 calories per day.
TDEE = 1345.25 * 1.375 = 1850 calories per day.
FAQ
What is the difference between BMR and TDEE?
BMR is the energy your body needs at complete rest to keep basic functions running, such as breathing and circulation. TDEE is your BMR plus the calories burned through daily movement, exercise, and digestion. TDEE is always higher than BMR and is the number you use to plan how much to eat.
Why is the Mifflin-St Jeor equation recommended?
It was published in 1990 and tested against measured resting metabolic rates. Research found it predicts resting energy within 10 percent of measured values more often than older equations like Harris-Benedict, which is why many dietitians treat it as the default choice for healthy adults.
How accurate is the result for me?
The equation gives a solid estimate for most healthy adults, but it does not measure your metabolism directly and does not account for body composition. People with very high muscle mass may burn more than the estimate, and the activity factor is a rough adjustment. Use the result as a starting point and adjust based on how your weight responds over a few weeks.
