Calorie calculator: BMR, TDEE and your daily calorie target
Maintenance calories, the deficit for weight loss and a macro split — every step of the calculation, not just the final number.
BMR, TDEE and maintenance calories, in order
BMR is what you would burn lying still all day — the cost of staying alive. This calculator uses the Mifflin-St Jeor equation, which current guidelines prefer over the older Harris-Benedict because it is more accurate in modern populations.
TDEE is BMR multiplied by an activity factor: everything you burn in a normal day, exercise included.
Target intake is TDEE plus or minus the adjustment for your goal. A 500 kcal daily deficit is the conventional starting point for losing roughly a pound a week.
How accurate is a calorie calculator
Mifflin-St Jeor predicts measured resting expenditure within 10% for about 80% of people. That leaves one person in five outside that band, and the equation was derived in adults with a BMI up to about 40, so it is least reliable at the extremes.
The activity multiplier is the larger source of error. Most people overestimate their activity level, and non-exercise movement — walking, standing, fidgeting — varies more between individuals than deliberate exercise does. If you are choosing between two levels, choose the lower one and adjust from what actually happens on the scale.
Using the calorie deficit for weight loss
The honest way to use this is to eat at the target for two to three weeks, track weight as a weekly average rather than day to day, and adjust by 100 to 200 calories based on what happened. The calculation gets you close; your own data closes the gap. There is more on why the arithmetic drifts as you get lighter in the calorie deficit article.
About the macro calculator split
Protein is set at 1.6 g per kilogram of body weight — the middle of the range that preserves muscle in a deficit. Fat is set at 25% of calories, above the threshold where hormone production suffers. Carbohydrate takes whatever is left, because it is the macronutrient with no established minimum requirement. Other splits are defensible; this one is a reasonable default rather than the only answer. See the protein calculator for the full range.
This is a calculator, not medical advice. The equations behind it describe populations and can be wrong about any individual. If you are pregnant, managing a health condition, taking medication, or recovering from an eating disorder, the number to act on is the one your doctor or a registered dietitian gives you.
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- Protein calculator Your daily protein intake in grams, set by what you are actually asking your body to do.
- Ideal weight calculator Four ideal body weight formulas side by side, plus the healthy weight range that is the more defensible target.
- Body fat calculator Estimate your body fat percentage with the US Navy tape method — three measurements, and an honest account of the error bars.
- Water intake calculator Your daily water intake from body weight, exercise and climate — and why thirst tracks the requirement better than this number does.