BMR & TDEE Calculator

BMR (Basal Metabolic Rate) is the calories you burn if you stayed in bed all day, sometimes called coma calories. TDEE (Total Daily Energy Expenditure) is your BMR plus the calories you burn moving, working, and exercising. You should base your diet on your TDEE, not your BMR.

Yes. Muscle tissue is metabolically active, meaning it burns calories even when you are resting. Fat tissue burns very few calories. This is why resistance training is excellent for long-term weight management: it raises your BMR.

Your BMR changes as your weight changes. We recommend re-calculating your numbers for every 5–10 lbs (2–5 kg) of body weight you lose or gain to ensure your calorie target remains accurate.

As we age, our metabolic processes naturally slow down, and we tend to lose some muscle mass (sarcopenia). The Mifflin-St Jeor equation accounts for this, which is why age is a required field. To combat this, focus on strength training to preserve muscle mass as you age.

Generally, no. Eating consistently below your BMR is not recommended. Your BMR represents the bare minimum energy required for your organs to function. Eating below this level can lead to nutrient deficiencies, muscle loss, and a slowed metabolism as your body tries to conserve energy. It is safer to create a calorie deficit from your TDEE, not your BMR.

There are several formulas used to calculate BMR, including the Harris-Benedict, Katch-McArdle, and Mifflin-St Jeor equations. We use the Mifflin-St Jeor equation because it is widely recognized as the most accurate for modern populations. If you check other sites using older formulas (like Harris-Benedict), you might see slight variations.

Technically, BMR does not include the Thermic Effect of Food (TEF), which is the energy used to digest what you eat. However, TEF typically accounts for about 10% of your daily energy expenditure and is usually factored into your TDEE activity multipliers rather than the raw BMR number.

"Starvation mode" is a popular term for adaptive thermogenesis. When you drastically cut calories for a long period, your body may lower its BMR to ensure survival, making weight loss harder. This is why moderate calorie deficits are superior to crash diets: they keep your metabolic rate higher for longer.

Pregnancy and breastfeeding significantly increase your body's energy demands. The standard formulas do not account for this. If you are pregnant or breastfeeding, please consult with a healthcare provider or use a specialized calculator, as you will likely need an additional 300–500 calories per day above your standard maintenance level.