RMR Calculator

RMR (kcal/day) = 10 × weight + 6.25 × height − 5 × age + s

weight

Body weight in kilograms (kg)

height

Height in centimetres (cm)

age

Age in whole years

s

+5 for men, −161 for women (kcal)

Use this page when you want the resting floor on its own — the number a diet should not sit far under. The equation is the same one the BMR calculator runs, so the two pages agree to the decimal; what differs is what they print around it. To turn the resting figure into a whole-day number, carry it to the TDEE calculator and pick an activity level there.

1. A 30-year-old man, 175 cm and 70 kg

   1. 10 × 70 = 700
   2. 6.25 × 175 = 1093.75
   3. 5 × 30 = 150
   4. 700 + 1093.75 − 150 + 5 = 1648.75 kcal
   5. Band: 1648.75 × 0.9 = 1484 and 1648.75 × 1.1 = 1814 kcal
   6. In kilojoules: 1648.75 × 4.184 = 6898 kJ

   The middle figure is what the equation returns; the two beside it are the range the equation is entitled to be wrong by. Reading 1649 as a measurement rather than an estimate is the mistake this page is built to prevent.

2. A 45-year-old woman, 163 cm and 82 kg

   1. 10 × 82 = 820
   2. 6.25 × 163 = 1018.75
   3. 5 × 45 = 225
   4. 820 + 1018.75 − 225 − 161 = 1452.75 kcal
   5. Band: 1452.75 × 0.9 = 1307 and 1452.75 × 1.1 = 1598 kcal
   6. In kilojoules: 1452.75 × 4.184 = 6078 kJ

   Age and sex pull in opposite directions from body size, which is why a heavier person can return a lower resting rate than a lighter one. The −161 for women and the −5 per year are both in the equation, and neither is a judgment about metabolism — they are the fit the study produced.

Two different 10% figures travel together here and they are not the same thing. The gap between RMR and BMR is about 10%, and it comes from the measurement conditions: BMR is taken on waking after at least twelve hours without food, lying still in a thermally neutral room, while RMR only asks for an awake, resting, postabsorptive state. The equation's error is also about 10%, but it measures something else — the distance between the prediction and what indirect calorimetry would read in the same person. The first says the two names label different measurements; the second says a prediction is not a measurement. It is fitted to adults, and assumes no thyroid disorder, no pregnancy and no acute illness.

RMR vs BMR: what is the difference?

They are two measurement protocols for the same quantity, and the stricter one reads lower. Basal metabolic rate is measured on waking after at least twelve hours without food, lying still in a thermally neutral room, with the mind at rest; resting metabolic rate drops the twelve-hour fast and the sleep requirement and asks only for an awake, resting, postabsorptive state with no exercise or food in the previous four to five hours. Relaxing the conditions lets the reading drift up by roughly 10%. In practice most calculators, including this one, run an RMR equation and call the answer BMR.

How accurate is a resting metabolic rate equation?

For any one person, about ±10%. In the validation study behind this page, the Mifflin equation came out more than 10% away from measured values in 22% of the subjects — so roughly one person in five should not trust the number to better than that. The equation is still the best of the simple ones for most adults, which is why it is the one used here rather than an older alternative.

Why is resting metabolic rate so high?

Because most of your daily energy goes to staying alive rather than to moving. The liver, brain, heart and kidneys together account for the majority of the resting figure, and skeletal muscle — the part people usually think of — is a smaller share of it than its weight suggests. That is also why adding muscle raises the number only modestly, and why cutting calories lowers it.

Can I raise my resting metabolic rate?

Only within limits, and body size is the strongest lever. Gaining muscle does raise the figure, but at a few kilocalories per kilogram of lean tissue per day — real, and much smaller than the change from gaining or losing weight overall. Undereating for a long stretch pushes the number down, since the body trims the organs' work as well as movement. No supplement has been shown to move it in a way that survives a trial, and no metabolism calculator can measure the effect of one anyway.

Should I eat below my resting metabolic rate?

Not without supervision. A target under your resting rate is what a very-low-calorie phase looks like, and guidelines put those under medical supervision because they are hard to hold and hard to come off. If a deficit lands you there, the usual fix is a slower rate of loss or more movement rather than a smaller plate. The calorie calculator flags a target under 1,200 kilocalories for the same reason.

• A new predictive equation for resting energy expenditure in healthy individuals — Mifflin MD, St Jeor ST, et al. — American Journal of Clinical Nutrition, 1990
• Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults: a systematic review — Frankenfield D, Roth-Yousey L, Compher C — Journal of the American Dietetic Association, 2005
• Validation of several established equations for resting metabolic rate in obese and nonobese people — Frankenfield DC, Rowe WA, Smith JS, Cooney RN — Journal of the American Dietetic Association, 2003
• Dietary Reference Intakes for Energy — National Academies of Sciences, Engineering, and Medicine — The National Academies Press, 2023