If you've ever wondered "how many calories should I eat a day?", the honest answer is: it depends on your TDEE. Nail that number and everything else — fat loss, muscle gain, or just maintaining — becomes simple math instead of guesswork.
What TDEE actually means
TDEE stands for Total Daily Energy Expenditure — the total number of calories your body burns in a day. It's made up of four parts:
- BMR (Basal Metabolic Rate): calories you'd burn lying in bed all day just keeping your organs running. Usually 60–70%.
- TEF (Thermic Effect of Food): energy used to digest what you eat, about 10%.
- NEAT: everything that isn't exercise — walking, fidgeting, doing dishes.
- Exercise: your workouts.
Add those up and you get the calories you burn on a typical day. Eat that amount and your weight stays stable.
How to estimate it
Most calculators use the Mifflin-St Jeor equation to find your BMR, then multiply by an activity factor:
- Sedentary (desk job, little exercise): BMR × 1.2
- Lightly active (1–3 days/week): BMR × 1.375
- Moderately active (3–5 days/week): BMR × 1.55
- Very active (6–7 days/week): BMR × 1.725
You need four things: your age, height, weight, and sex. That's it.
Turning your TDEE into a goal
Once you know your maintenance number, adjusting is straightforward:
- To lose fat: eat 300–500 calories below TDEE — a sustainable ~0.5–1 lb per week.
- To gain muscle: eat 200–400 calories above TDEE, train hard, and get enough protein (~0.7–1 g per pound of body weight).
- To maintain: eat at TDEE and adjust if the scale trends up or down over a few weeks.
The key word is trends. Your weight bounces day to day from water and food in your gut. Judge by the weekly average, not the morning-to-morning number.
Skip the manual equations
The Mifflin-St Jeor formula isn't something you want to do by hand every time your weight changes. I built a free calculator that does it for you — enter your stats and it gives your BMR, TDEE, and calorie targets for cutting, bulking, or maintaining, all at once.
👉 TDEETally — free TDEE & calorie calculator
No account, no upsell. Recalculate whenever your weight or activity changes.
The bottom line
TDEE is your maintenance calories — the anchor for any nutrition goal. Find it, pick a direction (deficit, surplus, or maintenance), track the weekly trend, and adjust every few weeks. It's not complicated once you have the number; it just requires being consistent long enough to see it work.
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