Mifflin-St Jeor calculator
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Your likely daily energy use
2,041 as low as
2,430 kcal/day
2,819 as high as
±16% — the shaded band is where your real figure most likely sits.
Show the arithmetic
- BMR (Mifflin-St Jeor)
- 10(82) + 6.25(178) − 5(34) + 5 = 1768 kcal
- Activity — Lightly active
- 1768 × 1.375 = 2430 kcal
- Honest band — ±16%
- 2041 – 2819 kcal/day
Mifflin-St Jeor is the default because it is the best-validated equation that needs no body-fat number. Harris-Benedict would give 1,848 kcal for the same person — a difference of well under 100 kcal. The formula is not what makes these calculators wrong; the activity multiplier is.
Where your calories go
Estimated daily breakdown of your 2,430 kcal TDEE.
- BMR (Resting) 1,768 kcal (73%)
Organs, brain & heart function at complete rest
- TEF (Food digestion) 243 kcal (10%)
Energy spent digesting protein, carbs & fats (~10%)
- NEAT (Daily movement) 294 kcal (12%)
Walking, standing, fidgeting & non-exercise movement
- EAT (Workouts) 126 kcal (5%)
Structured workouts, sports & cardio sessions
So what do I eat?
One recommendation, not a menu. Moderate loss is marked because it is the rate most people actually sustain. Pick another row to move the numbers.
1,944 kcal/day · -0.44 kg per week, estimated
Macros — as ranges, because that is what the evidence supports
- Protein 148–180 g 1.6–2.2 g per kg bodyweight, upper end while cutting
- Fat 43–65 g 20–30% of calories
- Carbs 160–241 g whatever the calorie target has left
How to replace this estimate with your own number
Every figure on this page is a starting point, and the ±band is the honest size of the error. After two to three weeks of eating near your target, weigh yourself daily and compare the weekly averages, not single days. If the average moved less than the estimate predicted, your real maintenance is lower than shown — subtract roughly 100 kcal and hold for another fortnight. If it moved faster, add 100. Two cycles of that beat any formula, including this one.
2–3 Week Self-Correction Calculator
Calculators estimate; your body provides ground truth. Enter your 2–3 week progress to calculate your actual real-world TDEE.
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What the Mifflin-St Jeor calculator does
The Mifflin-St Jeor calculator estimates your basal metabolic rate from four things you already know: weight, height, age and sex. It then multiplies that resting figure by an activity factor to produce your TDEE, and splits the result into protein, fat and carbohydrate for the goal you pick. The tool above is the same engine as the TDEE calculator on the homepage. This page exists because people search for the equation by name, and because the default here is worth explaining rather than burying.
Leave the body-fat field blank and the reading stays on Mifflin-St Jeor. Enter a measured body-fat percentage and the same tool switches to the Katch-McArdle equation, which works from lean mass instead. That switch is the whole of the formula choice on this site. There is no second calculator to keep in sync.
The Mifflin-St Jeor formula
Published in 1990 from a sample of 498 healthy adults, the equation is:
BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + swhere s is +5 for men and −161 for women. Weight in kilograms, height in centimetres, age in years.
Worked for a 35-year-old woman at 68 kg and 165 cm: 10 × 68 = 680, plus 6.25 × 165 = 1,031.25, minus 5 × 35 = 175, minus 161, which is a BMR of about 1,375 kcal. Multiply by an activity factor of 1.375 and the TDEE is about 1,891 kcal. The "Show the arithmetic" panel above already has your numbers in that same shape.
The sex term is not a round number pulled from nowhere. It is the offset that made the original regression fit men and women on one line, and it is the entire difference most calculators make when you toggle sex. The TDEE calculator for women unpacks what that offset captures and what it misses.
Why this site uses Mifflin-St Jeor as the default
A 2005 systematic review by Frankenfield, Roth-Yousey and Compher compared the common prediction equations against measured resting rate. Mifflin-St Jeor had the narrowest error range of the four they looked at, and it was the most reliable for both non-obese and obese adults in that sample. Later validation work put it within 10% of a measured resting rate for about 80% of healthy non-obese adults and about 70% of people with obesity.
That is not "the most accurate TDEE calculator on the internet." It is the best-validated weight-based equation for a general adult population, which is what a public calculator has to serve. The remaining fifth of people are missed by more than 10% at the resting step alone, and no height-and-weight formula can tell you whether you are in that group. That is why the reading above is a range, not a single confident figure. How accurate is a TDEE calculator walks through the evidence.
Mifflin-St Jeor vs Harris-Benedict vs Katch-McArdle
Three names show up in almost every comparison, and they are not equally worth switching between.
- Revised Harris-Benedict (Roza and Shizgal, 1984) is the older weight-based equation. For the same person it usually lands within 50–80 kcal of Mifflin-St Jeor. Switching to it does not fix an estimate that feels wrong. The activity multiplier, not the formula, is almost always the lever that moved.
- Mifflin-St Jeor is the default here because the published comparisons favour it for the general population, and because it needs no input you have to guess.
- Katch-McArdle is the one real upgrade, and only when two things are true: your body composition is away from average (lean, muscular, or heavy with muscle), and you have a measured body-fat percentage. With a guessed figure it is worse than Mifflin-St Jeor, while looking more precise.
This tool still computes Harris-Benedict and Cunningham in the background for the comparison lines in the arithmetic panel. They are there so you can see how little the formula choice usually moves, not because you should pick a favourite.
From BMR to TDEE, then to a plan
The Mifflin-St Jeor number is your BMR, the energy spent at complete rest. TDEE is that figure multiplied by an activity factor between 1.2 and 1.9. That multiplier is the entire difference between BMR and TDEE, and it is also where most of the uncertainty lives: moving one activity bucket changes the result by 150–250 kcal for most people, which dwarfs the gap between reputable formulas.
Used as a maintenance calories calculator, the TDEE above should hold your weight roughly steady. A fat-loss target is 10–25% below it; a lean-gain target is about 10% above. Protein is set from bodyweight at 1.6–2.2 g per kilogram; fat at 20–30% of calories; carbohydrate fills the rest. The macro calculator runs the same engine with the grams as the destination.
The best use of any of these numbers is as a starting point you intend to replace. Eat near the estimate for two to three weeks, weigh yourself daily, and compare weekly averages. If the average moved less than predicted, drop about 100 kcal and hold. Two rounds of that beat every equation on this page, including Mifflin-St Jeor, because your own trend already contains the things no formula can see.
What this calculator cannot tell you
It cannot see your non-exercise movement, your sleep, your medical history, or whether you are in the fifth of people whose resting rate the equation misses by more than 10%. It also cannot verify that the activity bucket you picked matches your actual week, which is the input most likely to be wrong.
This page is written by Madhu Kinnera, who is not a clinician. Nothing here is medical advice. The equation and the accuracy comparisons above come from the primary literature: Mifflin, St Jeor et al. (1990) for the formula itself, and Frankenfield, Roth-Yousey and Compher (2005) for why it is the default. If you are pregnant, have a condition affecting your metabolism, or are planning a large change in intake, speak to a doctor or a registered dietitian first.
Frequently asked questions
What is the Mifflin-St Jeor equation?
A 1990 prediction of basal metabolic rate from weight, height, age and sex: BMR = 10 × kg + 6.25 × cm − 5 × age, then +5 for men or −161 for women. Multiply that resting figure by an activity factor between 1.2 and 1.9 to get TDEE. It is the default equation on this site because published comparisons find it the most reliable of the common weight-based formulas.
How do I calculate Mifflin-St Jeor by hand?
Take 10 times your weight in kilograms, add 6.25 times your height in centimetres, subtract 5 times your age in years, then add 5 if you are male or subtract 161 if you are female. That is your BMR in kcal. Multiply by 1.2, 1.375, 1.55, 1.725 or 1.9 depending on how active your week actually is.
Is Mifflin-St Jeor more accurate than Harris-Benedict?
Slightly, for the general adult population. Frankenfield’s 2005 review found Mifflin-St Jeor had the narrowest error range of the common equations. In practice the two usually agree to within 50–80 kcal for the same person, which is less than one activity-bucket step. Switching formulas rarely fixes an estimate that feels wrong.
Mifflin-St Jeor vs Katch-McArdle: which should I use?
Mifflin-St Jeor if you do not have a measured body-fat percentage. Katch-McArdle if you do, and your body composition is away from average (lean, muscular, or heavy with muscle). With a guessed body-fat number, Katch-McArdle is usually worse than Mifflin-St Jeor while looking more precise. Leave the body-fat field blank unless the figure is real.
What is the Mifflin-St Jeor formula for women?
The same four-term equation, with the sex offset set to −161 kcal instead of +5. That offset is the entire sex-specific part of the estimate. There is not a separate women’s formula. If you have a measured body-fat percentage, Katch-McArdle drops the sex term altogether and works from lean mass.
Do I need my body fat percentage for Mifflin-St Jeor?
No. Weight, height, age and sex are the only inputs. That is the point of using it as a default: nothing has to be estimated. A measured body-fat figure lets this same tool switch to Katch-McArdle. A guessed one should stay out of the field.
Is this a Mifflin-St Jeor TDEE calculator?
Yes. The reading above is your Mifflin-St Jeor BMR multiplied by the activity factor you picked, which is your TDEE, then split into macros for your goal. The equation only estimates the resting step. Everything after it is the same as on the other calculators on this site.
Who created the Mifflin-St Jeor equation?
Mifflin, St Jeor, Hill, Scott, Daugherty and Koh, published in the American Journal of Clinical Nutrition in 1990. The sample was 498 healthy adults. It was intended to replace Harris-Benedict for a more contemporary population, and later reviews generally found that it did.
Why does switching sex change my number so much?
Because the equation applies −161 kcal for women and +5 kcal for men, a 166 kcal gap at the resting step before activity is applied. After an activity multiplier of 1.55 that is about 250 kcal of TDEE. It reflects average differences in body composition, not a judgement about how anyone should eat.
Does Mifflin-St Jeor work if I am very muscular or have obesity?
It is a population average, so it is weaker at the extremes. For muscular people with a measured body-fat percentage, Katch-McArdle is usually the better first estimate. For higher body-fat ranges, Frankenfield’s review still favoured Mifflin-St Jeor among the common equations, and it needs no body-fat input.
How accurate is a Mifflin-St Jeor calculator?
Validation work puts it within 10% of a measured resting rate for about four in five healthy non-obese adults. The remaining fifth are missed by more, and the activity multiplier adds error on top. Treat the output as carrying roughly ±16% of real uncertainty, which is why this tool draws a band rather than one figure.
Should I eat at my Mifflin-St Jeor BMR to lose weight?
No. Eat below your TDEE, typically 10–25% below, not at your BMR. Eating at BMR subtracts your entire activity allowance at once and usually produces a deficit that is too large to sustain. BMR is an input. TDEE is the number to plan against.
How often should I recalculate?
After every 5–10 kg of weight change, or whenever a target that used to move the scale has quietly stopped. Between recalculations, two to three weeks of weekly weight averages are a better instrument than re-running the equation. The formula cannot see the adaptation your scale already recorded.
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