How to use the BMR Calculator
- Choose your sex and enter your age.
- Choose metric or imperial units.
- Enter your weight and height.
- The result updates instantly as you type. There is no button to press.
- Use Copy result to copy the figures, or Copy link to share a link that reopens the BMR Calculator with the same inputs.
How it works
Your basal metabolic rate (BMR) is the energy your body uses to stay alive at complete rest: breathing, circulating blood, keeping warm, and running the brain and organs. For most people it accounts for around 60–70% of the calories they burn each day, more than all physical activity combined.
BMR is measured precisely in a lab after fasting and resting, but predictive equations estimate it well for most adults. This calculator uses the Mifflin-St Jeor equation (1990), which reviews by dietetics organisations have found to be the most accurate of the common equations for healthy adults, typically within about 10% of measured values. The revised Harris-Benedict equation (1984) is shown for comparison. It tends to give a slightly higher result.
BMR rises with body size, because there is more tissue to maintain, and falls with age, partly because muscle mass declines. Men usually have a higher BMR than women of the same size because they carry more muscle on average. Equations cannot see body composition, so very muscular people may burn more than predicted and people with a high body fat percentage may burn less. To turn BMR into a daily calorie target, multiply it by an activity factor, as the table shows, or use the TDEE calculator.
Formula
W is weight in kg, H height in cm and A age in years. Result in kilocalories (kcal) per day; multiply by 4.184 for kilojoules.
Example
A 30-year-old man weighing 70 kg and 175 cm tall: 10 × 70 + 6.25 × 175 − 5 × 30 + 5 = 700 + 1,093.75 − 150 + 5 = 1,649 kcal a day. The revised Harris-Benedict equation gives about 1,696 kcal. A woman with the same measurements would have a Mifflin-St Jeor BMR of about 1,483 kcal, because the constant is −161 instead of +5.
Frequently asked questions
What is the difference between BMR and RMR?
Resting metabolic rate (RMR) is measured under less strict conditions than BMR and is usually slightly higher. In everyday use the two terms are often treated as the same thing.
Should I eat my BMR in calories?
Most people should eat more than their BMR, because BMR excludes all movement and digestion. Your daily needs are your BMR times an activity factor. Eating below BMR for long periods is not usually recommended without medical guidance.
How can I increase my BMR?
Building muscle through strength training raises BMR modestly, because muscle uses more energy than fat at rest. Staying active and eating enough protein help preserve muscle as you age.
Disclaimer: This calculator provides general estimates for education only and is not medical advice, diagnosis or treatment. Formulas are based on population averages and may not fit your body, age, pregnancy or health conditions. Talk to a doctor, midwife or registered dietitian before making decisions about your health.