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TDEE calculator (Mifflin-St Jeor)
Work out how many calories you actually burn each day, then what to eat to lose fat or build muscle. No email required — the answer is right here.
BMR
1,759
kcal/day at complete rest
Your TDEE
2,550
kcal/day to maintain weight
Lose fat: 2,040 kcal/dayA 20% deficit — roughly 0.5–0.7kg a week.
Build muscle: 2,805 kcal/dayA 10% surplus — lean gain, minimal fat.
What is TDEE?
TDEE stands for Total Daily Energy Expenditure — every calorie your body burns in a day. It is the single most useful number in nutrition, because every goal is defined relative to it: eat below your TDEE and you lose weight, eat above it and you gain, eat at it and you hold.
TDEE is built from four parts. Your Basal Metabolic Rate (BMR) is what you would burn lying still all day, and it accounts for roughly 60–70% of the total. The thermic effect of food — the energy used digesting what you eat — is about 10%. Then there is deliberate exercise, and finally NEAT, the non-exercise activity of walking, fidgeting and standing, which varies enormously between people and explains much of why two similar bodies burn different amounts.
How this calculator works
We use the Mifflin-St Jeor equation, published in 1990 and now the formula most widely recommended by registered dietitians because it predicts resting energy expenditure more accurately than the older Harris-Benedict equation for most modern populations.
Men: BMR = (10 × kg) + (6.25 × cm) − (5 × age) + 5
Women: BMR = (10 × kg) + (6.25 × cm) − (5 × age) − 161
TDEE = BMR × activity multiplier
The activity multiplier runs from 1.2 for a sedentary desk worker up to 1.725 for someone with a physical job who also trains hard most days. Most people who train three to five times a week and otherwise sit at a desk land between 1.45 and 1.6. Be honest here — overestimating activity is the most common reason a calorie target fails to produce results.
How accurate is it?
Treat the output as an informed starting point, not a measurement. Any predictive equation carries roughly a 10% margin either side, because it cannot see your body composition, thyroid function, medication, sleep or genetics. Two people with identical stats can differ by several hundred calories a day.
The practical approach: eat at the calculated number for two to three weeks, track your weight each morning under the same conditions, and use the weekly average rather than any single day. If the average has not moved in the direction you want after a fortnight, adjust by 150–200 calories and repeat. Your real TDEE is whatever number actually produces the change you are after — the equation just gets you close enough to start.
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