BMR Calculator
Estimate the calories your body burns at rest, plus your daily total by activity level.
Learn how it works: What Is BMR (Basal Metabolic Rate)?Enter your weight, height, and age to see your BMR.
How to use the BMR calculator
Four inputs drive the result: your sex, weight, height, and age. Fill them in and the estimate appears on the right.
- Choose metric (kg and cm) or imperial (lb, feet, inches).
- Select your sex. The formula uses a different constant for each.
- Enter your weight, height, and age in years.
- Read your BMR at the top, then check the table for daily calories at five activity levels.
What is BMR?
BMR is your basal metabolic rate. It is the energy your body spends to keep you alive while you do nothing at all: breathing, pumping blood, repairing cells, holding your temperature steady. Even on a day spent in bed, your body burns this baseline.
Most adults spend the largest share of their daily calories this way. The exact figure shifts with muscle mass, genetics, hormones, and history. Two people of the same size can sit a few hundred calories apart. So read your BMR as a well-grounded estimate rather than an exact reading from a lab.
BMR vs maintenance calories
BMR alone does not cover a full day. Walking, working, cooking, and exercise all add to it. Multiply your BMR by an activity factor and you get maintenance calories: roughly what it takes to hold your current weight.
The table next to the calculator does this for you. A desk-bound day uses a factor of 1.2. Hard daily training pushes it toward 1.9. Most people land somewhere in the middle. These factors are broad averages, so pick the row that best matches a typical week rather than your best or worst day.
The Mifflin-St Jeor formula
This calculator uses Mifflin-St Jeor, the equation many dietitians favor for its accuracy across modern populations:
Men: 10 × kg + 6.25 × cm − 5 × age + 5
Women: 10 × kg + 6.25 × cm − 5 × age − 161
Take a 30-year-old man at 80 kg and 180 cm. That is 800 plus 1,125, minus 150, plus 5, which lands at 1,780 calories a day. Swap to the women's constant and the same size and age gives about 1,614. The gap reflects average differences in body composition, not a judgment about any one person.
Frequently asked questions
- What is the difference between BMR and TDEE?
- BMR is what you burn at complete rest. TDEE, or total daily energy expenditure, is BMR plus everything you do in a day. The activity table on this page turns your BMR into a TDEE estimate.
- How accurate is the BMR calculator?
- Mifflin-St Jeor is one of the more reliable equations for healthy adults, but it is still an estimate. Muscle mass, genetics, and hormones all shift the real number. A clinic can measure it directly if you need precision.
- Should I eat my BMR in calories to lose weight?
- Eating at or below your BMR for long stretches is not advised without medical supervision, since BMR does not cover daily activity. If you have a weight goal, a doctor or registered dietitian can set a safe target with you.
- Does BMR change with age?
- Yes. BMR tends to ease down over the years as muscle mass declines and metabolism slows. That is why the formula subtracts a small amount for each year of age.
- Why does sex change the result?
- On average, men carry more lean tissue, which burns more energy at rest, so the formula adds for men and subtracts for women. It is a population average and will not fit everyone exactly.
- Can I use BMR to plan my meals?
- It is a useful reference point for understanding your energy needs. For a real meal plan, especially with a health condition, talk to a registered dietitian who can account for your full situation.