BMR Calculator

Your body is burning calories right now, even if you are sitting perfectly still. Every breath you take, every heartbeat, and the quiet work of keeping your body warm all cost energy. That resting burn has a name: your BMR, or basal metabolic rate. When you calculate BMR, you learn how many calories your body needs just to keep you alive for 24 hours, before a single step, chore, or workout is counted.

Here is the quick answer: a 30-year-old man who weighs 80 kg and is 180 cm tall has a BMR of about 1,780 kcal a day. But every body runs a different-sized engine, so your own number could be quite different. Use the calculator below to calculate your BMR in seconds. Just enter your sex, age, weight, and height, and your result appears right away.

What Is BMR?

BMR stands for basal metabolic rate. In plain words, it is the amount of energy your body spends at complete rest just to stay alive. If you stayed in bed all day without moving a muscle, your body would still burn calories to keep your heart beating, your lungs breathing, your brain thinking, and your body temperature steady. That is your BMR at work.

This resting burn is bigger than most people expect. For the average person, BMR makes up about 60 to 70 percent of all the calories burned in a day. It is usually the biggest slice of your daily total by far. Exercise and daily movement matter, but your resting body is doing most of the burning.

You may also see the term RMR, which stands for resting metabolic rate. RMR is measured under looser, more comfortable conditions than BMR. For an RMR test you do not need to fast overnight or sleep in the lab, so the reading usually comes out a little higher. In everyday life, though, the two words point at nearly the same number, so you can treat them as the same thing when you plan your eating.

How We Calculate Your BMR

Our calculator uses the Mifflin-St Jeor formula, developed by researchers in 1990 and still trusted by most dietitians today. Study after study has found it the most accurate of the common formulas for most people, usually landing within about 10 percent of a laboratory measurement.

The math itself is simple. For men, the formula is: 10 x weight in kilograms + 6.25 x height in centimetres - 5 x age in years + 5. Let us work through it with our example: a 30-year-old man who weighs 80 kg and is 180 cm tall. First, 10 x 80 = 800. Then 6.25 x 180 = 1,125. Then 5 x 30 = 150. Put it together: 800 + 1,125 - 150 + 5 = 1,780. That is his BMR: 1,780 kcal per day.

For women, the formula is almost the same, except the last step is - 161 instead of + 5. Take a 30-year-old woman who weighs 65 kg and is 165 cm tall: 10 x 65 = 650, plus 6.25 x 165 = 1,031.25, minus 5 x 30 = 150, minus 161. That gives 650 + 1,031.25 - 150 - 161 = 1,370.25, or about 1,370 kcal per day. The lower number mostly reflects that women, on average, carry less muscle than men of the same weight.

You will notice the calculator also shows a second number from the older Harris-Benedict formula, first published in 1919 and revised in 1984. For our example man, Harris-Benedict gives 1,854 kcal a day, close to the Mifflin-St Jeor result of 1,780 but not identical. We show both on purpose, because honest tools admit that every formula is an estimate. The two trusted formulas usually land within about 5 to 10 percent of each other, and your true BMR is very likely sitting somewhere near both of them.

From BMR to Your Real Daily Calories

Your BMR is only the resting floor: the calories you would burn lying still all day. Real life adds movement on top of that, from walking to the kitchen to climbing stairs to working out. To find your full daily burn, which dietitians call your TDEE (total daily energy expenditure), you multiply your BMR by an activity factor. The calculator above does this math for you automatically, but here is the full picture using our example BMR of 1,780:

Activity level	Multiplier	Daily calories
Sedentary (desk job, little exercise)	x 1.2	2,136
Lightly active (exercise 1-3 days a week)	x 1.375	2,448
Moderately active (exercise 3-5 days a week)	x 1.55	2,759
Very active (exercise 6-7 days a week)	x 1.725	3,071
Athlete (hard training twice a day)	x 1.9	3,382

This full-day number is the one that matters when you plan your meals. If you want a complete maintenance plan built with this same method, try our Maintenance Calories Calculator. And if your goal is to lose weight, our TDEE Weight Loss Calculator builds safe daily targets starting from your BMR.

What Affects Your BMR?

No two BMRs are exactly alike. Several factors set yours, and while you cannot change all of them, the most powerful one is in your hands.

Muscle mass. Muscle burns more energy than fat, even at complete rest. A kilogram of muscle uses noticeably more calories around the clock than a kilogram of fat, which is why two people of the same weight can have very different BMRs. Of everything on this list, muscle is the biggest lever you control.

Age. BMR drifts down slowly as we get older, roughly 1 to 2 percent per decade after early adulthood. Most of that drop is not really about age itself. It happens because we slowly lose muscle over the years, and less muscle means a slower resting burn.

Body size. Bigger bodies run bigger engines. A taller, heavier person needs more energy simply to keep everything running, so BMR rises with weight and height. This is why the formula uses your exact weight and height instead of an average.

Sex. Men usually have a higher BMR than women of the same age and weight, mainly because they typically carry more muscle. The formula handles this with + 5 for men and - 161 for women.

Smaller factors. Genetics deals each of us a slightly different starting hand, so some people simply run a little hotter than others. Thyroid hormones and general health also tune the rate up or down. And long, very hard dieting can push BMR down for a while, because the body tries to save energy when food is scarce.

Can You Raise Your BMR?

Yes, you can, but let us be honest about what actually moves the needle. You cannot change your age, your height, or your genes. What you can change is the biggest lever of all: your muscle.

Build and keep muscle. Resistance training two to three times a week tells your body to hold on to muscle, and more muscle means a higher BMR. Bodyweight exercises, dumbbells, resistance bands, and machines all count.

Eat enough protein. Protein gives your body the building blocks it needs to maintain muscle, and this matters most when you are eating a little less to lose weight. Without enough protein, a calorie deficit can eat into muscle along with fat, which drags your BMR down.

Move more across the whole day. Beyond workouts, the little things add up: more daily steps, taking the stairs, standing instead of sitting, and parking a little farther away. Researchers call this NEAT, short for non-exercise activity thermogenesis, and it can differ by hundreds of calories a day between two otherwise similar people.

Sleep well. Poor sleep disturbs the hormones that control hunger, recovery, and muscle repair. Good sleep makes it easier to keep your muscle and harder to overeat, which protects your BMR from both sides.

One gentle myth-busting note: chili peppers, green tea, and ice-cold water do nudge calorie burn up a tiny bit, but the effect is so small that it will not change your results in any meaningful way. They are not a plan. Muscle and movement are the plan.

Your BMR is the floor of your calorie house: every eating plan stands on it. Now that you know yours, read our guide on how many calories should I eat daily to see the full picture, from maintenance to healthy weight loss.