Mifflin-St Jeor Equation: BMR Formula With Worked Examples
The Mifflin-St Jeor equation, published in 1990, is the most accurate BMR prediction formula for the general population. Here is the formula for men and women, worked through step by step with real numbers, plus what to know about its limits.
The Mifflin-St Jeor equation estimates BMR from weight, height, age, and sex. For men: BMR = (10 x weight in kg) + (6.25 x height in cm) - (5 x age) + 5. For women: the same formula, minus 161 instead of plus 5. Multiply the result by an activity factor from 1.2 to 1.9 to get TDEE.
The formula
For men:
BMR = (10 x weight in kg) + (6.25 x height in cm) - (5 x age) + 5
For women:
BMR = (10 x weight in kg) + (6.25 x height in cm) - (5 x age) - 161
The weight term is the heaviest contributor: every kilogram of body weight adds 10 calories to daily BMR. Height adds 6.25 calories per centimeter, reflecting larger organs and more tissue. The age term subtracts 5 calories per year of age, and the sex constant accounts for the average body composition difference: women carry more body fat and less muscle at the same weight, so the formula subtracts 161 instead of adding 5.
Worked example: a man
A 35 year old man, 180 cm tall, weighing 80 kg:
Weight term: 10 x 80 = 800
Height term: 6.25 x 180 = 1125
Age term: 5 x 35 = 175
BMR = 800 + 1125 - 175 + 5 = 1755 calories per day
Moderately active, his TDEE is 1755 x 1.55 = 2720 calories per day. (See how to calculate TDEE for the full four-step process.)
Worked example: a woman
A 28 year old woman, 165 cm tall, weighing 60 kg:
Weight term: 10 x 60 = 600
Height term: 6.25 x 165 = 1031.25
Age term: 5 x 28 = 140
BMR = 600 + 1031.25 - 140 - 161 = 1330 calories per day
Lightly active, her TDEE is 1330 x 1.375 = 1829 calories per day.
Using pounds and inches
The formula needs metric units. Convert first:
Kilograms = pounds divided by 2.205
Centimeters = inches multiplied by 2.54
Example: a 176 lb man who is 70 inches tall. Kilograms = 176 / 2.205 = 79.8. Centimeters = 70 x 2.54 = 177.8. Plug those into the formula exactly as above.
How accurate is Mifflin-St Jeor?
It is the best general-purpose BMR formula we have, but it is still an estimate. In validation studies, Mifflin-St Jeor predicts resting metabolic rate within 10 percent of measured values for most people, and it outperforms the older Harris-Benedict equation, which tends to overestimate BMR for modern populations, often by 5 to 15 percent.
Individual results vary. Very muscular people burn more than the formula says, because muscle is metabolically active and the equation does not know your body composition. Very lean or very obese individuals can also fall outside the sweet spot. That is why any calorie target built from this formula should be treated as a starting point and confirmed against the scale over two to four weeks, adjusting in 100 to 200 calorie steps.
Formulas that include body fat percentage, like Katch-McArdle, can be slightly more accurate if you have a reliable body fat measurement. Most people do not, which is why Mifflin-St Jeor remains the practical default, and it is what our free TDEE calculator uses.
Run the formula on your own stats
Our free calculator applies the Mifflin-St Jeor equation to your age, sex, height, and weight, adds your activity level, and returns your BMR, TDEE, and calorie targets for losing, maintaining, or gaining weight.
Mifflin-St Jeor questions
What is the Mifflin-St Jeor equation?
It is a BMR prediction formula published by Mifflin and colleagues in 1990. It estimates basal metabolic rate from weight, height, age, and sex: for men, (10 x weight in kg) + (6.25 x height in cm) - (5 x age) + 5; for women, the same with -161 instead of +5. It is the most validated BMR equation for the general population.
Is Mifflin-St Jeor the most accurate BMR formula?
For people without a measured body fat percentage, yes. Validation studies show it beats Harris-Benedict and Owen equations for the average adult, predicting resting metabolic rate within 10 percent for most. If you have an accurate body fat measurement, the Katch-McArdle formula can edge it out slightly.
How do I use the formula with pounds and inches?
Convert first: kilograms = pounds / 2.205, centimeters = inches x 2.54. A 176 lb, 70 inch man becomes 79.8 kg and 177.8 cm, which plug straight into the formula. Our calculator has a metric/imperial switch that does this for you.
Why do men and women use different constants?
The +5 for men and -161 for women reflect average body composition differences. At the same weight, women typically carry more body fat and less muscle than men, and muscle burns more calories at rest than fat. The constants absorb that difference so the same formula structure works for both.