🔥Calorie & TDEE calculator
Find the exact calories to lose fat, maintain or build muscle, using the Mifflin–St Jeor formula lifters trust.
Maintenance keeps your weight stable. Adjust with the scale every 2 weeks.
How this calculator works
Your body burns energy in two parts. The first is what it costs simply to stay alive - breathing, circulating blood, keeping you warm. That is your BMR, and it is the larger share for almost everyone. The second is everything you do on top: walking, training, fidgeting, digesting.
BMR is estimated with the Mifflin-St Jeor equation, which has held up better than the older Harris-Benedict against measured metabolic rates:
men: BMR = 10 x kg + 6.25 x cm - 5 x age + 5
women: BMR = 10 x kg + 6.25 x cm - 5 x age - 161That figure is then multiplied by an activity factor to give TDEE - the calories that keep your weight where it is today. Musclory uses this exact equation for the targets it sets you, so the number here and the number in the app agree.
A worked example
A 30-year-old man, 80 kg, 180 cm, training four times a week:
BMR = 10x80 + 6.25x180 - 5x30 + 5 = 1780 kcal
TDEE = 1780 x 1.55 (moderate) = 2759 kcalTo lose fat he eats below that, to build muscle above it. A deficit of roughly 20% - about 2200 kcal here - takes weight off at a rate most people can hold without losing strength or sleep.
What to do with the number
Treat it as a starting point, not a verdict. Every equation estimates an average, and real people sit either side of it. Eat at the number for two weeks, weigh yourself at the same time on the same days, and take the trend rather than any single reading - daily weight swings by a kilo or more on water alone.
- Losing more than about 1% of bodyweight a week costs muscle. Add 200 kcal.
- Not moving at all after three weeks means the estimate was high for you, or the food log is missing something. Take 200 kcal off.
- Gaining 0.25-0.5% of bodyweight a week is enough. Faster than that is mostly fat.
Common questions
Is Mifflin-St Jeor accurate?
It is the most accurate of the widely used equations, and it is still an estimate - expect it to land within about 10% for most people. That is why you adjust from the scale rather than trusting the first number.
Should I eat back the calories I burn training?
Only partly. The activity multiplier you picked already includes your training, so eating your workout calories back on top counts them twice. Musclory credits burned calories separately and lets you switch that off for exactly this reason.
Why do I need more calories than someone my weight?
Height, age, sex and muscle mass all move BMR. Two people at the same weight can differ by several hundred calories a day, which is why bodyweight alone is a poor guide.
Do I need to eat the same amount every day?
No. Your body works on a rolling average, not a calendar day. Hitting the weekly total matters far more than hitting it evenly - Musclory supports a different target per weekday for exactly this.
Sources
Mifflin MD, St Jeor ST, et al. "A new predictive equation for resting energy expenditure in healthy individuals." The American Journal of Clinical Nutrition, 1990. Activity multipliers follow the standard sedentary-to-very-active scale used with it.
Estimates for general fitness guidance, not medical advice.