BMR Calculator
Your resting burn in calories per day, with a per-kilogram and per-pound figure.
| BMR (Mifflin-St Jeor) | 1,718 kcal/day 10 x kg + 6.25 x cm - 5 x age + 5 |
|---|---|
| Per kilogram | 22.9 kcal/kg |
| Per pound | 10.4 kcal/lb |
| If you barely move | 2,061 kcal/day x1.2 sedentary |
| Harris-Benedict estimate | 1,777 kcal/day older formula, for comparison |
Approximate shares for a healthy adult at rest; they shift with body composition and training history.
What basal metabolic rate measures
Basal metabolic rate is the energy your body uses to stay alive at complete rest: breathing, circulating blood, repairing tissue, running the brain and keeping organs at temperature. It is measured in a laboratory after an overnight fast, lying still, in a thermoneutral room - which is why almost every online figure is actually an estimate of resting metabolic rate rather than a true basal measurement.
The two terms are close enough that they are used interchangeably, and this calculator follows that convention. What matters is the size of the number: for most adults resting energy is 60% to 70% of everything burned in a day, so it sets the floor under every calorie target you will ever set.
| Body part or process | Share of resting burn |
|---|---|
| Liver and gut | about 25% |
| Brain | about 20% |
| Skeletal muscle | about 20%, more in trained people |
| Heart and kidneys | about 15% |
| Everything else | the remainder, mostly tissue repair |
How the BMR formula works
The equation behind this page is Mifflin-St Jeor, published in 1990 and still the default recommendation for healthy adults: 10 x weight in kilograms + 6.25 x height in centimetres - 5 x age, plus 5 for men and minus 161 for women. Every input is necessary. Height and weight scale the amount of tissue you are keeping alive, and age subtracts a small amount per year for the gradual loss of lean mass that most people experience.
The page also shows the Harris-Benedict equation, published in 1919 and widely used before Mifflin-St Jeor was validated. It typically returns a figure a few percent higher, sometimes more in younger and heavier people. Seeing both is more honest than pretending a single equation is exact: published comparisons put Mifflin-St Jeor within roughly 10% of measured resting energy in healthy adults.
Reading your BMR result
The first row is your resting burn for a full day, not per hour. The per-kilogram and per-pound rows are a quick way to sanity-check the figure: most adults land between 20 and 25 kcal per kilogram of body weight per day, with leaner and younger people higher and older or heavier people lower per kilogram.
The last two rows show what happens when you add movement. Multiplied by 1.2 - a day with no exercise at all - resting energy still rises by a fifth, because sitting, standing, cooking and walking to the bathroom all cost energy. That gap between BMR and daily burn is where most weight management actually happens.
| Group | Typical resting burn | Per kilogram |
|---|---|---|
| Women, 18-30 | 1,300 to 1,600 kcal | about 21 to 24 kcal/kg |
| Women, 31-60 | 1,200 to 1,500 kcal | about 20 to 23 kcal/kg |
| Men, 18-30 | 1,600 to 2,000 kcal | about 22 to 25 kcal/kg |
| Men, 31-60 | 1,500 to 1,900 kcal | about 21 to 24 kcal/kg |
BMR, RMR and TDEE: what is the difference?
Resting metabolic rate and basal metabolic rate describe almost the same thing, measured under slightly different conditions. RMR is the looser measurement - you rest but do not have to sleep in a laboratory - and it usually comes out 3% to 5% higher than a true BMR. For everyday decisions the difference is smaller than the error in the equation.
TDEE is the number that includes everything else: RMR plus digestion, plus every step and fidget, plus training. If BMR is the floor, TDEE is the actual daily spend. Never set a food target from BMR alone - a 1,700 kcal resting burn does not mean 1,700 kcal is a sensible intake, because it ignores the 20% to 70% you burn on top.
A worked example
A 30-year-old man at 178 cm and 75 kg: 10 x 75 is 750, 6.25 x 178 is 1,112.5, 5 x 30 is 150, and the male constant adds 5. That gives 750 + 1,112.5 - 150 + 5, which is 1,718 kcal a day at rest.
A 30-year-old woman at 165 cm and 60 kg: 10 x 60 is 600, 6.25 x 165 is 1,031.25, 5 x 30 is 150, and the female constant subtracts 161. The result is 600 + 1,031.25 - 150 - 161, about 1,320 kcal a day. Adding a light training week at 1.375 lifts her daily burn to roughly 1,815 kcal.
Can you change your BMR?
Only slowly, and less than the fitness industry suggests. Adding a kilogram of muscle raises resting burn by roughly 10 to 15 kcal a day, so a serious two-year gain of 5 kg of muscle is worth about 50 to 75 kcal a day - real, but smaller than one biscuit. Losing muscle does the reverse, which is the main reason aggressive dieting makes maintenance harder over time.
What clearly moves the number downwards is chronic under-eating and inactivity, because both reduce lean mass and the energy cost of daily movement. Age subtracts slowly through the same route. The honest conclusion: BMR is a fairly stable personal constant, and daily movement is the part you can actually change this month.
Frequently asked questions
What is a normal BMR?
About 1,200 to 1,600 kcal a day for women and 1,500 to 2,000 for men, with younger and larger people at the top of those ranges. A number far outside them usually means a unit mistake rather than a medical problem.
Can I raise my BMR?
Slightly. Muscle costs about 10 to 15 kcal per kilogram per day at rest, so a hard-won 5 kg of muscle is worth roughly 50 to 75 kcal a day. Movement burns far more than resting metabolism, so adding steps changes your daily total much faster.
Why does my BMR fall on a diet?
Because you are losing tissue, and because a smaller body moves more cheaply. Part of the drop is genuine metabolic adaptation and part is simply lower body weight. This is why targets are recalculated as you lose weight.
Is BMR the same as metabolism?
People say 'metabolism' to mean resting burn most of the time, but the full daily picture is TDEE. Two people with identical BMR can differ by 600 kcal a day purely through movement.
Should I eat at my BMR to lose weight?
No - eating at resting burn means a deficit far larger than 20%, which costs muscle and is hard to sustain. Work from TDEE and cut 15% to 20% from there.
Does BMR change with age?
It falls gradually, mostly because lean mass falls. The Mifflin-St Jeor equation subtracts 5 kcal per year of age, which captures the average trend rather than a law of nature; training keeps the decline slower.
Sources
- Mifflin MD et al., A new predictive equation for resting energy expenditure in healthy adults (1990)
- Frankenfield D et al., Comparison of predictive equations for resting metabolic rate
- NIH: Body weight and metabolism
Formulas and thresholds are taken from the sources above. They are a starting point for adults, not a diagnosis.
Last reviewed September 12, 2026. How we calculate · Editorial policy