Updated
Mifflin-St Jeor equation: formula, worked examples and accuracy
The Mifflin-St Jeor equation estimates resting energy use from weight, height, age and sex. For men: 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5. For women, subtract 161 instead of adding 5. It was published in 1990 from a study of 498 adults, and it gives an estimate, not a measurement.
These are example numbers. Enter your own above.
Your maintenance calories, as a range across equations
Each equation's BMR × 1.2 for your activity level. Mean of the equations 2,157 kcal/day, and the equations disagree by 90 kcal.
Your activity choice moves this estimate more than the equations disagree. One step to “Lightly active” moves the mean about 314 kcal/day, while the equations on your row span 90 kcal/day.
Is exercise already included? Yes. The “Sedentary” multiplier (×1.2) already covers your workouts and daily movement. Do not add calories burned in the gym on top of this number. Double-counting exercise is the most common reason these estimates come out too high.
| Mifflin-St Jeor | 2,112 kcal |
|---|---|
| Revised Harris-Benedict | 2,202 kcal |
| Katch-McArdle | add body fat % to include it |
| Activity level | Factor | Maintenance |
|---|---|---|
| Sedentaryselected | ×1.2 | 2,112–2,202 kcal |
| Lightly active | ×1.375 | 2,420–2,523 kcal |
| Moderately active | ×1.55 | 2,728–2,844 kcal |
| Very active | ×1.725 | 3,036–3,165 kcal |
| Extra active | ×1.9 | 3,344–3,486 kcal |
Show the work
Each equation estimates your basal metabolic rate (BMR), the energy you use at complete rest, from your sex, age, height and weight. Katch-McArdle instead uses lean body mass, which is why it needs a body fat percentage. Every BMR is then multiplied by your activity factor (×1.2) to reach maintenance calories. The range you see is the spread between equations, not a margin of error for your body.
Your weight, height, age, sex and body fat stay in this browser, on this device. Nothing is uploaded, there is no account, and no other company receives any of it. The button below deletes what this page stored, where this browser allows it.
Supported inputs: ages 18–80; height 130–230 cm (4 ft 3 in – 7 ft 7 in); weight 35–250 kg (77–551 lb); body fat 8–55% or blank. Imperial figures are rounded; metric limits are exact. Results are shown in whole calories per day.
What is the Mifflin-St Jeor equation?
The Mifflin-St Jeor equation predicts resting energy expenditure, or REE. The original paper uses that term, while calculators, this site included, label the result BMR. The output is an estimate of kilocalories per day from four inputs: weight, height, age and sex. The equation was published by Mifflin, St Jeor and colleagues in the American Journal of Clinical Nutrition in 1990 (Mifflin et al., 1990). The result is typically multiplied by an activity factor to estimate total daily energy use.
The Academy of Nutrition and Dietetics Evidence Analysis Library names Mifflin-St Jeor the most accurate equation for estimating RMR in overweight and obese adults when RMR cannot be measured. Its recommendation is rated "Strong, Conditional" (Academy of Nutrition and Dietetics Evidence Analysis Library). That statement applies to the population and condition named, not to every person.
The Mifflin-St Jeor formula for men and women
Mifflin-St Jeor formula for men
BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age (years) + 5
Mifflin-St Jeor formula for women
BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age (years) − 161
The formula in pounds and inches
For pounds and inches, the same equation is:
BMR = 4.536 × weight (lb) + 15.875 × height (in) − 5 × age (years) + 5 for men
BMR = 4.536 × weight (lb) + 15.875 × height (in) − 5 × age (years) − 161 for women
This version folds the unit conversions into the coefficients. The weight coefficient comes from 10 × 0.4536 per pound. The height coefficient comes from 6.25 × 2.54 per inch. The worked man below gives 1,760.0 with either unit system.
| Weight | Height | Age | Constant | |
|---|---|---|---|---|
| Men | 10 × kg | 6.25 × cm | − 5 × years | + 5 |
| Women | 10 × kg | 6.25 × cm | − 5 × years | − 161 |
Some sources show 9.99 and 4.92 instead of 10 and 5. The paper first fitted this unsimplified regression: REE = 9.99 × weight + 6.25 × height − 4.92 × age + 166 × sex (male 1, female 0) − 161. The authors state that simplifying it and splitting it by sex "did not affect its predictive value." The 166-unit gap between the male +5 and female −161 constants matches the sex coefficient in that regression. The two versions give near-identical results. Neither is an error.
How to calculate BMR with the Mifflin-St Jeor equation
The maintenance calorie calculator applies the same type of calculation through its input fields. The manual process has three steps:
- Convert weight to kilograms and height to centimeters, unless using the pounds-and-inches version.
- Multiply weight, height and age by their formula terms. Weight uses 10 or 4.536, height uses 6.25 or 15.875, and age uses −5 in every case.
- Add 5 for men or subtract 161 for women. This constant is the only term that changes by sex.
Worked example: a 30-year-old man, 5 ft 10 in, 175 lb
This body is 79.38 kg and 177.8 cm:
10 × 79.38 + 6.25 × 177.8 − 5 × 30 + 5
793.8 + 1,111.25 − 150 + 5 = 1,760 kcal/day
Worked example: a 30-year-old woman, 5 ft 5 in, 140 lb
This body is 63.50 kg and 165.1 cm:
10 × 63.50 + 6.25 × 165.1 − 5 × 30 − 161
635.0 + 1,031.9 − 150 − 161 = 1,356 kcal/day
| Step | Man, 30, 5 ft 10 in, 175 lb | Woman, 30, 5 ft 5 in, 140 lb |
|---|---|---|
| Conversion | 79.38 kg, 177.8 cm | 63.50 kg, 165.1 cm |
| Weight term | 793.8 | 635.0 |
| Height term | 1,111.25 | 1,031.9 |
| Age term | −150 | −150 |
| Constant | +5 | −161 |
| Result | 1,760 kcal/day | 1,356 kcal/day |
From BMR to daily calories: activity factors
A daily estimate can be calculated as:
BMR × activity factor = daily estimate
For the man with a 1,760 kcal BMR, the five activity factors produce these figures:
| Factor | Level | Description | Daily estimate |
|---|---|---|---|
| 1.2 | Sedentary | Desk job and little deliberate exercise. Most days are spent sitting. | 2,112 |
| 1.375 | Lightly active | Light exercise 1-3 days a week, or a job that keeps you on your feet part of the day. | 2,420 |
| 1.55 | Moderately active | Moderate exercise 3-5 days a week, or steady walking and standing most of the day. | 2,728 |
| 1.725 | Very active | Hard exercise 6-7 days a week, or physical work such as construction or nursing shifts. | 3,036 |
| 1.9 | Extra active | Hard daily exercise plus a physical job, or twice-a-day training. | 3,344 |
The 1.2-1.9 scale is a widely used convention from the Harris-Benedict tradition. It is not the output of a validation study, and a search of the primary literature found no source for the individual values.
For this man, moving from 1.375 to 1.55 adds 308 kcal. Switching from Mifflin-St Jeor to revised Harris-Benedict adds 75 kcal. Picking the activity level moves the answer about four times as much as picking the equation.
Where the Mifflin-St Jeor equation comes from
The equation comes from a 1990 study that measured resting energy expenditure with indirect calorimetry. Its authors were Mifflin, St Jeor, Hill, Scott, Daugherty and Koh (Mifflin et al., 1990).
| Published | Am J Clin Nutr 1990;51(2):241-7, doi:10.1093/ajcn/51.2.241, PMID 2305711 |
| Subjects | 498 healthy adults: 247 women, 251 men |
| Age | 19-78 years (mean 45, SD 14) |
| Weight status | 264 normal-weight, 234 obese |
| Measurement | Resting energy expenditure by indirect calorimetry |
| Fit | R² = 0.71 |
Fat-free mass was the best single predictor in that study. The fat-free mass equation was REE = 19.7 × FFM + 413, with R² 0.64, compared with 0.56 for weight alone (Mifflin et al., 1990). The standard Mifflin-St Jeor equation does not use fat-free mass as an input.
The Academy notes that the equation "was not tested on racial groups other than Caucasian and so may not be accurate for these groups" (Academy of Nutrition and Dietetics Evidence Analysis Library).
How accurate is the Mifflin-St Jeor equation?
The Academy's figures apply to obese individuals. Mifflin-St Jeor was within 10% of measured RMR in 70% of obese individuals. Up to 9% of estimates were over the measured value, and up to 21% were under it.
For comparison, Harris-Benedict with actual weight was within 10% in 39-64% of cases, with up to 43% over and up to 35% under. Owen was within 10% in 33-51% of cases (Academy of Nutrition and Dietetics Evidence Analysis Library). These are group results. Any one person can sit well outside them.
In the 1990 study, the 1919 Harris-Benedict equations overestimated measured REE by 5%, with p < 0.01, in its 498 subjects (Mifflin et al., 1990).
Where the equation is less reliable
The equation was derived from adults aged 19-78. Use outside that age range is extrapolation from the study population. The study did not test racial groups beyond Caucasian subjects.
Lean mass was not an input in the standard equation, yet it was the strongest single predictor in the same study. As an inference from that result, people with unusually high or low lean mass for their body weight can differ from the estimate.
Mifflin-St Jeor vs Harris-Benedict and Katch-McArdle
The same body can produce different BMR estimates because each equation uses different coefficients or inputs. All four equations below use the same two bodies so the differences come only from the formulas themselves. The revised Harris-Benedict figures below use the 1984 revision (Roza and Shizgal, 1984). The original Harris-Benedict figures use the 1919 equation (Harris and Benedict, 1919).
| Body | Mifflin-St Jeor | Revised Harris-Benedict (1984) | Original Harris-Benedict (1919) | Katch-McArdle |
|---|---|---|---|---|
| Man, 30, 5 ft 10 in, 175 lb | 1,760 | 1,835 | 1,845 | 1,742 (at 20% body fat) |
| Woman, 30, 5 ft 5 in, 140 lb | 1,356 | 1,416 | 1,428 | 1,330 (at 30% body fat) |
For these two bodies, both Harris-Benedict versions come in 60-85 kcal above Mifflin-St Jeor, and Katch-McArdle comes in slightly below it. The Academy prefers Mifflin-St Jeor for overweight and obese adults when RMR cannot be measured (Academy of Nutrition and Dietetics Evidence Analysis Library).
When Katch-McArdle fits better
Katch-McArdle needs a body fat percentage. It works from lean mass, which the 1990 study found to be the best single predictor of REE. Its result is only as good as the body fat figure entered. The table uses 20% body fat for the man and 30% for the woman.
Frequently asked questions
Is the Mifflin-St Jeor equation BMR or RMR?
It was built to predict resting energy expenditure (Mifflin et al., 1990). Calculators call the result BMR by convention.
What is the most accurate BMR equation?
No equation is most accurate for everyone. For overweight and obese adults, the Academy of Nutrition and Dietetics names Mifflin-St Jeor when RMR cannot be measured (Academy of Nutrition and Dietetics Evidence Analysis Library).
Does the Mifflin-St Jeor equation include exercise?
No. It estimates resting energy. Movement comes in through the activity factor.
Why do some sources show 9.99 and 4.92?
They print the unsimplified regression from the paper (Mifflin et al., 1990). It gives near-identical results to the simplified men and women formulas.
What is the MSJ equation?
MSJ is shorthand for Mifflin-St Jeor. It refers to the same equation shown above.
Can I use Mifflin-St Jeor without knowing my body fat?
Yes. Body fat is not an input in Mifflin-St Jeor. Katch-McArdle is the equation in the comparison that uses body fat percentage.
Sources
- Mifflin MD, St Jeor ST, Hill LA, Scott BJ, Daugherty SA, Koh YO. Am J Clin Nutr 1990;51(2):241-7. doi:10.1093/ajcn/51.2.241. PMID 2305711
- Roza AM, Shizgal HM. Am J Clin Nutr 1984;40(1):168-82. doi:10.1093/ajcn/40.1.168. PMID 6741850
- Harris JA, Benedict FG. A Biometric Study of Basal Metabolism in Man. Carnegie Institution of Washington, Publication 279, 1919
- Academy of Nutrition and Dietetics, Evidence Analysis Library: Adult Weight Management, Determination of Resting Metabolic Rate.
- McArdle WD, Katch FI, Katch VL. Exercise Physiology.
This calculator provides general information, not medical or nutritional advice. It does not diagnose or treat any condition. Talk to a qualified clinician or registered dietitian before making significant changes to what you eat.
Written by the Maintenance Calorie Calculator editorial team.