Calculate your Basal Metabolic Rate (BMR). Find out how many calories your body needs just to survive at rest.
Calories/day at rest
This guide is for educational purposes and is not medical advice. See our Disclaimer and consult a qualified healthcare professional before making changes to your diet or exercise routine.
Your Basal Metabolic Rate (BMR) is the number of calories your body burns while performing the basic functions that keep you alive, measured while you are at complete rest. It is the energy your body spends on tasks you never think about, such as:
Think of BMR as your body's "idle" setting: the calories you would burn if you spent the entire day resting in bed without moving, eating, or digesting. For most adults, BMR accounts for roughly 60 to 70 percent of the total calories burned each day, which is why it is such a useful starting point for any nutrition plan.
BMR is only the baseline. It does not include the energy you spend walking, working, exercising, or even digesting food. To estimate how much you should actually eat in a day, you need your TDEE (Total Daily Energy Expenditure), which layers your daily activity on top of your BMR:
TDEE = BMR × Activity Level Factor
In short, BMR is what your body needs to simply exist, while TDEE is what your body needs to get through a real day. If you want to lose, maintain, or gain weight, TDEE is the number you compare your food intake against, not BMR alone.
This calculator uses the Mifflin-St Jeor equation, which was published in 1990 and is widely regarded as one of the most accurate BMR estimates for the general population. It uses your weight in kilograms, height in centimetres, and age in years. The only difference between the sexes is the final constant:
The equation adds calories for weight and height (larger bodies need more energy) and subtracts calories for age (metabolism tends to ease as we get older). If you enter your weight and height in pounds and inches, this calculator converts them to metric for you before applying the formula, so you don't have to do any conversions by hand.
You may also see the older Harris-Benedict equation, first developed in 1919 and revised in 1984. It works in a similar way but tends to overestimate calorie needs slightly for many people, which is why most modern tools, including this one, prefer Mifflin-St Jeor.
Getting your estimate takes only a few seconds. Using the form at the top of this page:
Your BMR Score updates automatically in the results panel as you type, shown as calories per day at rest. There is no submit button to press, so feel free to adjust the numbers and watch how each factor changes the result.
Suppose a 30-year-old man weighs 180 lb and stands 70 in tall. First we convert to metric: 180 lb is about 81.6 kg, and 70 in is about 177.8 cm. Plugging those into the men's formula:
That figure is his BMR, the energy his body needs at complete rest. A woman with the exact same weight, height, and age would use −161 instead of +5, giving a BMR of roughly 1,616 calories per day.
No two people share the same BMR, and several factors explain the differences:
BMR on its own does not tell you how much to eat, because almost nobody spends all day in bed. To turn your BMR into a realistic daily target, multiply it by an activity factor to get your TDEE. Someone sedentary might multiply by around 1.2, while a very active person might use 1.7 or more. From there you adjust up or down depending on your goal: eat below your TDEE to lose weight, at your TDEE to maintain, or above it to gain.
Our TDEE Calculator handles the activity multiplier for you, and the Calorie Calculator helps you set a target for a specific weight goal.
A few myths about metabolism come up again and again:
While genetics set part of the baseline, some habits genuinely help:
Now that you know your baseline number, calculate your total daily needs.
Your BMR is relatively stable but can fluctuate slightly due to hormonal changes, illness, or extreme environmental temperatures.
Yes. The most effective way to increase BMR is to build muscle mass. Muscle tissue burns more calories at rest than fat tissue.
They are very similar. BMR (Basal Metabolic Rate) is measured under strict laboratory conditions (fasted, no movement). RMR (Resting Metabolic Rate) is less strict and includes small movements like eating or stretching. For most people, they are effectively the same.
This calculator uses the Mifflin-St Jeor equation, published in 1990. Research has found it to be more accurate for the modern general population than the older Harris-Benedict equation, which is why most dietitians and clinicians now prefer it.
A BMR formula gives a solid estimate for most people, usually within about 10 percent of a lab measurement. It cannot account for your exact body composition, so someone with a lot of muscle may burn more than the estimate, and the only truly precise method is indirect calorimetry in a clinic.
No. Your BMR is the bare minimum your body needs at complete rest, and eating at or below it for long periods is generally too aggressive. For weight loss you should base your target on your TDEE (BMR multiplied by an activity factor) and create a moderate deficit from there.
Yes, it tends to decline gradually with age, largely because we often lose muscle mass over time. Staying active and doing resistance training helps preserve lean muscle, which keeps your BMR higher than it would otherwise be.
Understanding BMR is the first step to sustainable weight control.
Now Calculate TDEEThe information on this page is based on guidance from the following authoritative sources:
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