BMR Calculator (Basal Metabolic Rate)
Find out how many calories your body burns at rest with this free BMR calculator. It also shows your total daily calorie needs (TDEE) based on your activity level, and how many calories to eat to lose, maintain or gain weight.
What is BMR?
Basal Metabolic Rate (BMR) is the number of calories your body needs to stay alive while completely at rest. Even when you are asleep, your body uses energy to breathe, pump blood, keep your temperature stable, repair cells and keep your brain working. For most people, BMR makes up around 60–70% of all the calories they burn in a day, which makes it the foundation of any calorie or diet plan.
BMR vs TDEE: what is the difference?
BMR only covers the calories you burn at rest. TDEE (Total Daily Energy Expenditure) is your BMR plus everything else: walking, working, exercising and even digesting food. TDEE is the number that matters for weight control. If you eat about your TDEE, your weight stays stable. Eat less and you lose weight, eat more and you gain weight. You should not eat below your BMR for long periods without medical guidance.
BMR formula (Mifflin-St Jeor equation)
This calculator uses the Mifflin-St Jeor equation, which research has found to be one of the most accurate formulas for estimating BMR in healthy adults:
Men: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5
Women: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161
Example: A 30-year-old man who weighs 70 kg and is 175 cm tall has a BMR of (10 × 70) + (6.25 × 175) − (5 × 30) + 5 = 1,649 kcal/day. A 30-year-old woman who weighs 60 kg and is 160 cm tall has a BMR of 1,289 kcal/day. If both are moderately active, their TDEE is about 2,556 and 1,998 kcal/day.
Activity multipliers used for TDEE
| Activity level | Description | Multiplier |
|---|---|---|
| Sedentary | Desk job, little or no exercise | BMR × 1.2 |
| Lightly active | Light exercise 1–3 days a week | BMR × 1.375 |
| Moderately active | Moderate exercise 3–5 days a week | BMR × 1.55 |
| Very active | Hard exercise 6–7 days a week | BMR × 1.725 |
| Extra active | Physical job or training twice a day | BMR × 1.9 |
Most people overestimate how active they are. If you are unsure, choose the lower level and adjust after a few weeks based on your results.
What affects your BMR?
Several factors change how many calories you burn at rest. Muscle mass is the biggest one you can control, because muscle burns more energy than fat, even at rest. Age matters too, as BMR slowly falls over the years, mainly because of muscle loss. Sex plays a role, since men usually have more muscle and a higher BMR than women of the same size. Body size also counts, as taller and heavier people burn more. Genetics, hormones (especially thyroid hormones), sleep and very low calorie diets can also raise or lower BMR.
How to use your BMR for weight loss or gain
To lose weight, eat a little less than your TDEE. A deficit of about 500 calories a day leads to a loss of roughly 0.5 kg (about 1 lb) per week for many people, although results vary. To gain weight or build muscle, eat around 300–500 calories above your TDEE and combine it with strength training. Avoid very large deficits, because they can lower your metabolism, cause muscle loss and make weight harder to keep off. For a full daily plan, try our Calorie Calculator, split your calories into protein, carbs and fat with the Macro Calculator, and check your weight category with the BMI Calculator.
How to boost your metabolism naturally
You cannot change your age or height, but you can support a healthy metabolism. Build muscle with regular strength training, eat enough protein at every meal, stay active throughout the day, get 7–8 hours of sleep, drink enough water (see our Water Intake Calculator), and avoid crash diets that cut calories too sharply.
Frequently Asked Questions
What is a normal BMR?
There is no single normal BMR, because it depends on your age, sex, height and weight. As a rough guide, many adult women have a BMR of around 1,200–1,500 kcal/day and many adult men around 1,500–1,900 kcal/day.
How accurate is this BMR calculator?
The Mifflin-St Jeor equation is usually accurate to within about 10% for most healthy adults. It may be less accurate for very muscular people, older adults and people with certain medical conditions. Only a lab test such as indirect calorimetry can measure BMR exactly.
Should I eat my BMR to lose weight?
No. Eating only your BMR is usually too low, because it ignores the calories you burn through daily activity. Base your intake on your TDEE minus a moderate deficit instead, and do not eat below your BMR for long without medical advice.
Why do men have a higher BMR than women?
Men usually have more muscle mass and less body fat than women of the same weight. Since muscle burns more calories at rest, men tend to have a higher BMR.
Does BMR decrease with age?
Yes. BMR tends to drop gradually with age, mainly because people lose muscle over time. Regular strength training and enough protein can help slow this decline.
What is the difference between BMR and RMR?
BMR is measured under very strict resting conditions, while Resting Metabolic Rate (RMR) is measured under less strict conditions and is usually slightly higher. In everyday use, the two terms are often used to mean the same thing.