BMR Calculator
Enter your sex, age, height and weight to estimate your basal metabolic rate, the calories your body uses at rest. The main result uses the Mifflin-St Jeor equation, the same one Counter44 uses for its daily target. The revised Harris-Benedict result sits beside it for comparison. Heights in feet and inches and weights in pounds are converted exactly (1 in = 2.54 cm, 1 lb = 0.45359237 kg). Prefer not to say averages the male and female equations. A table shows estimated calories a day for no workouts up to 6 or more a week. Results are estimates, not medical advice.
BMR Calculator
Your details
Units
Imperial and Metric keep their own entries. Switching shows the other set and doesn't convert what you typed.
Sex
Prefer not to say averages the male and female equations, as Counter44 does.
Mifflin-St Jeor was built from adults aged 19 to 78. Outside that range, treat the result as a rougher estimate.
10 × kg + 6.25 × cm − 5 × age − 161
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| Workouts per week | Estimate |
|---|---|
| No workouts (sedentary) · ×1.2 | — kcal |
| 1–2 workouts a week (light) · ×1.375 | — kcal |
| 3–5 workouts a week (moderate) · ×1.55 | — kcal |
| 6+ workouts a week (very active) · ×1.725 | — kcal |
Estimated calories a day: your Mifflin-St Jeor BMR times the factor Counter44 uses for your workouts per week. Not a calorie target: no weight-loss or gain adjustment and no minimum are applied.
BMR here is predicted from an equation, not measured. Results are estimates, not medical advice.
Counter44
Calorie Tracker
Turn your BMR into a daily calorie target
Counter44's guided setup runs this same Mifflin-St Jeor math with your workouts per week and goal, then sets a daily target you log meals against.
Free · No sign-up needed
How this BMR calculator works
The main result uses the equations Mifflin, St Jeor and colleagues published in 1990 (American Journal of Clinical Nutrition). They built them from resting energy measured by indirect calorimetry in 498 healthy adults aged 19 to 78, 247 women and 251 men. The simplified versions are:
- Men: 10 × weight (kg) + 6.25 × height (cm) − 5 × age (years) + 5
- Women: 10 × weight (kg) + 6.25 × height (cm) − 5 × age (years) − 161
Prefer not to say uses −78, which is (5 − 161) ÷ 2. That gives exactly the average of the male and female results, the same rule Counter44 uses.
Imperial entries are converted first. Feet × 12 + inches gives total inches, and inches × 2.54 gives centimeters. Pounds × 0.45359237 gives kilograms. Both factors are exact by definition (NIST Handbook 44, NIST SP 811). Dividing pounds by 2.2 is a common shortcut, but it isn't exact: it turns 155 lb into 70.45 kg and the default result into 1,400. The "Calculated from" line under your result shows the kilograms and centimeters the equation used.
The defaults describe a 35-year-old woman at 5 ft 5 in and 155 lb, which is 70.30681735 kg and 165.1 cm. So 703.0681735 + 1,031.875 − 175 − 161 = 1,398.9431735, shown as 1,399 kcal a day. Rounding happens once, at the end. Rounding the inputs first can move the answer: 70 kg gives 1,396.
Imperial and Metric keep separate entries, so switching doesn't convert what you typed. The metric defaults, 165 cm and 70 kg, are a slightly different body and give 1,395. Type the exact conversion and the results match: for a 40-year-old man, 182.88 cm and 90.718474 kg give the same 1,855 kcal as 6 ft 0 in and 200 lb.
The calculator accepts ages 13 to 100, the same range as Counter44's setup. The equation came from adults aged 19 to 78, so for teens and people over 78, treat the result as a rougher estimate.
Mifflin-St Jeor or Harris-Benedict: why the two numbers differ
The comparison uses the revised Harris-Benedict equations from Roza and Shizgal (1984):
- Men: 88.362 + 13.397 × kg + 4.799 × cm − 5.677 × age
- Women: 447.593 + 9.247 × kg + 3.098 × cm − 4.330 × age
- Prefer not to say: the average of the two, which works out to 267.9775 + 11.322 × kg + 3.9485 × cm − 5.0035 × age
Roza and Shizgal recalculated the 1918-1919 equations, adding data Benedict published later on 98 people across a wider age range, and got equations similar to the originals. They reported that the equations predict resting energy "with a precision of +/- 14%" in normally nourished people, but are unreliable in malnourished patients. The original constants (the 66.47 and 655.1 versions) belong to a different equation, and many calculators don't say which one they use. That's why this page labels its comparison "revised Harris-Benedict (1984)".
Mifflin and St Jeor found that "the Harris-Benedict Equations derived in 1919 overestimated measured REE by 5%." A 2005 systematic review of the four most-used equations (Frankenfield et al., Journal of the American Dietetic Association) concluded that "the Mifflin-St Jeor equation was the most reliable, predicting RMR within 10% of measured in more nonobese and obese individuals than any other equation, and it also had the narrowest error range." The same review warned that "noteworthy errors and limitations exist when it is applied to individuals", and that older adults and US-residing ethnic minorities were underrepresented in the studies.
Harris-Benedict usually comes out higher, but not always. For the default woman it gives 1,458 against Mifflin-St Jeor's 1,399. For an 80-year-old man at 190 cm and 70 kg it gives 1,484 against 1,493. The difference line compares the two numbers as displayed, so it always matches what's on screen: a 35-year-old woman at 165 cm and 70 kg sees 1,455 and 1,395, a 60 kcal gap, though the unrounded gap is 59.25.
Equations that use body fat, such as Katch-McArdle, need a body-fat measurement, which this calculator doesn't ask for.
From BMR to calories a day
BMR covers the body at complete rest. The National Academies' Dietary Reference Intakes for Energy (2023) put resting metabolic rate at about 10% above BMR and say it "accounts for ~60-70% of total daily energy expenditure". Digestion and movement make up the rest, so every row in the table comes out above your BMR.
The table multiplies your Mifflin-St Jeor BMR by the factor Counter44 uses for workouts per week:
- No workouts (sedentary): × 1.2
- 1–2 workouts a week (light): × 1.375
- 3–5 workouts a week (moderate): × 1.55
- 6 or more workouts a week (very active): × 1.725
For the default woman the rows come to 1,679, 1,924, 2,168 and 2,413 kcal a day. These estimate energy use; they aren't recommended intakes. Each row multiplies the unrounded BMR, so a row can be 1 kcal off the displayed BMR times the factor. At 165 cm and 70 kg the 3–5 row shows 2,163, because 1,395.25 × 1.55 = 2,162.64.
No row is a calorie target. The page applies no deficit, no surplus and no minimum. Counter44's minimums of 1,200 kcal (female), 1,350 (prefer not to say) and 1,500 (male) apply to the target it computes after the goal step, not to BMR.
Age enters each equation as a fixed amount per year: 5 kcal in Mifflin-St Jeor, and 5.677 (men) or 4.33 (women) in revised Harris-Benedict. A 2021 study in Science (Pontzer et al.) measured total daily energy expenditure, not BMR, in people aged 8 days to 95 years. Adjusted for fat-free mass, it "remains stable in adulthood (20 to 60 years), even during pregnancy" and then declines in older adults.
Using your BMR with Counter44
Counter44's guided setup runs the same Mifflin-St Jeor math, including the Prefer not to say average, from your height and weight in metric or imperial. It multiplies by your workouts-per-week factor and applies your goal: 500 kcal less to lose, 300 more to gain or no change to maintain. It keeps the result at or above the minimum for your sex option and splits it 30% protein, 40% carbs and 30% fat. The result is a daily calorie target and macro grams.
Calories, protein, carbs and fat are each tap-to-edit, and editing one makes the target manual. Logging a weight or saving Your profile recomputes the target, and if you set it by hand, the app asks first. If you change the macro grams, the macros to calories calculator checks that they add up to your calories.
Track exercise is off by default. You type in calories burned yourself; the app doesn't estimate them. If your workouts per week already set your factor, adding logged workouts on top counts them twice. The exercise calories eat-back calculator shows the effect.
The target only helps if what you log is accurate. Weigh portions with the food calories by weight calculator, get per-serving numbers for home cooking with the recipe calorie calculator, and read how to calorie count homemade food. Set up your daily target in Counter44.
Other Counter44 calculators are listed on the tools page as they are published.
This calculator and the figures on this page are estimates for planning, not medical advice. If you have a medical condition, are pregnant, or have a history of disordered eating, talk to a doctor or registered dietitian before changing how you eat.
Frequently Asked Questions
Common questions about bmr calculator
What does a BMR calculator actually estimate?
It estimates basal metabolic rate, the energy your body uses at "complete physical, mental, and digestive rest," as the National Academies define it. A lab measures BMR right after sleep, at least 12 hours after eating. A calculator can't measure anything: it predicts the number from your weight, height, age and sex. Mifflin-St Jeor, the equation this page leads with, was built from resting measurements by indirect calorimetry in 498 healthy adults. The National Academies put resting rate at about 10% above BMR, so this result, like most "BMR" calculators', is closer to a resting rate. The two terms are often used interchangeably. Either way it's an estimate, not medical advice.
How do I calculate my BMR by hand?
Convert to metric first: pounds × 0.45359237 gives kilograms, and total inches × 2.54 gives centimeters. Then apply Mifflin-St Jeor: 10 × kg + 6.25 × cm − 5 × age, plus 5 for men or minus 161 for women. Take a 35-year-old woman at 5 ft 5 in and 155 lb. That's 70.30681735 kg and 165.1 cm, so 703.0681735 + 1,031.875 − 175 − 161 = 1,398.9431735, about 1,399 kcal a day. Round only at the end. Rounding her weight to 70 kg first gives 1,396 instead.
Why do Mifflin-St Jeor and Harris-Benedict give different numbers?
They're separate equations fitted to different groups of people. Harris and Benedict published theirs in 1918 and 1919, and Roza and Shizgal refit them in 1984, adding later data Benedict collected over a wider age range. They reported that the equations predict resting energy "with a precision of +/- 14%" in normally nourished people. Mifflin and St Jeor built their 1990 equation from 498 adults aged 19 to 78, and found that the 1919 Harris-Benedict equations overestimated measured resting energy by 5%. For the default 35-year-old woman, revised Harris-Benedict gives 1,458 kcal against Mifflin-St Jeor's 1,399. The gap can flip, though: an 80-year-old man at 190 cm and 70 kg gets 1,484 from Harris-Benedict and 1,493 from Mifflin-St Jeor. A 2005 systematic review (Frankenfield et al., Journal of the American Dietetic Association) found Mifflin-St Jeor "the most reliable, predicting RMR within 10% of measured in more nonobese and obese individuals than any other equation."
What happens if I choose "Prefer not to say"?
Both equations come in male and female versions only, and no published equation covers anyone else. This calculator does what Counter44 does and averages the male and female results. For Mifflin-St Jeor, that replaces the +5 or −161 with −78, which is (5 − 161) ÷ 2. The result always sits 83 kcal below the male result and 83 above the female result for the same body. For revised Harris-Benedict it averages the two full equations, which works out to 267.9775 + 11.322 × kg + 3.9485 × cm − 5.0035 × age. It's a midpoint between two validated equations, not a separately tested one.
Is a higher or lower BMR better?
Neither. BMR mostly tracks body size: Mifflin's paper found fat-free mass was the best single predictor of resting energy. In the equation, each kilogram adds 10 kcal (about 4.5 per pound), each centimeter adds 6.25 (about 15.9 per inch) and each year of age takes off 5, and men come out 166 kcal above women of the same size. A taller or heavier person gets a higher number without being any healthier. And for any one person, the estimate can be off. The Frankenfield review found Mifflin-St Jeor the equation most likely to land within 10% of a measured rate, and still noted "noteworthy errors and limitations" for individuals. Only a lab test with indirect calorimetry measures yours.
Does BMR go down as you get older?
In the equations it drops by a fixed amount each year: 5 kcal in Mifflin-St Jeor, and 5.677 (men) or 4.33 (women) in revised Harris-Benedict. Real people are less tidy. A 2021 study in Science (Pontzer et al.) measured total daily energy use in people aged 8 days to 95 years. Once adjusted for fat-free mass, it "remains stable in adulthood (20 to 60 years)" and then declines in older adults. That study measured total expenditure, not BMR, so treat any equation's age term as an average, not a rule for you. Recalculate when your weight changes, since weight moves the estimate too.
What do the calories by activity level mean?
Each row is your Mifflin-St Jeor BMR multiplied by one of the four factors Counter44 uses for workouts per week: ×1.2 for none, ×1.375 for 1–2, ×1.55 for 3–5 and ×1.725 for 6 or more. Each one estimates what you'd burn in a day at that activity level. None of them is a calorie target: no weight-loss cut or gain surplus is applied, and no minimum. The rows multiply the unrounded BMR, so a row can be 1 kcal off from the displayed BMR times the factor. If your workouts already set your factor, adding the calories from those workouts back to your daily goal counts them twice. The exercise calories eat-back calculator shows the effect.
Does Counter44 use the same formula as this calculator?
For the first steps, yes. Counter44's guided setup asks for your sex (Male, Female or Prefer not to say), birth date, height and weight in metric or imperial, workouts per week and goal. It estimates resting energy with Mifflin-St Jeor, averaging the male and female results for Prefer not to say, and multiplies by your workouts-per-week factor. Then it applies your goal (500 kcal less to lose, 300 more to gain), keeps the target at or above 1,200 kcal for women, 1,350 for prefer not to say or 1,500 for men, and splits it 30% protein, 40% carbs and 30% fat. Harris-Benedict appears only on this page, for comparison. Every target is editable, and logging a new weight recomputes it. If you set the target by hand, the app asks first.