"2,000 calories a day" is printed on every nutrition label — and it's wrong for almost everyone reading it. That number is a labeling average, not your number. The calories you burn depend on your size, sex, age, and how much you move, and the figure that captures all of it is your TDEE. Get it right and every diet decision downstream — losing fat, gaining muscle, maintaining — becomes simple subtraction.

What TDEE actually means

TDEE (Total Daily Energy Expenditure) is the total number of calories you burn in a day, all in. It's built from four parts:

  • BMR (Basal Metabolic Rate) — what your body burns at complete rest just to stay alive: heartbeat, breathing, brain, organs. This is the big one, usually 60–70% of the total.

  • TEF (Thermic Effect of Food) — the energy spent digesting what you eat, roughly 10%.

  • NEAT (Non-Exercise Activity Thermogenesis) — walking, fidgeting, standing, chores. Wildly variable between people.

  • EAT (Exercise Activity) — deliberate workouts. For most people this is smaller than they think.

Add them up and you have your maintenance calories — the amount that keeps your weight exactly where it is.

Step 1: calculate your BMR

The modern standard is the Mifflin-St Jeor equation:

  • Men: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5

  • Women: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161

A 30-year-old woman, 68 kg, 168 cm: (10 × 68) + (6.25 × 168) − (5 × 30) − 161 = 680 + 1,050 − 150 − 161 = 1,419 calories at complete rest. The BMR calculator runs this instantly in metric or imperial.

Step 2: multiply by your activity level

BMR is rest only — now scale it for how much you move:

Activity level

Description

Multiplier

Sedentary

Desk job, little exercise

× 1.2

Lightly active

Light exercise 1–3 days/week

× 1.375

Moderately active

Exercise 3–5 days/week

× 1.55

Very active

Hard exercise 6–7 days/week

× 1.725

Extra active

Physical job + training

× 1.9

Our example woman, lightly active: 1,419 × 1.375 = ~1,951 calories/day. That's her TDEE — eat that and she maintains. The TDEE calculator does both steps together, so you never touch the arithmetic.

Step 3: adjust for your goal

TDEE is the pivot point. From there:

  • Lose fat: eat below TDEE. A deficit of ~500 cal/day ≈ 0.5 kg (1 lb) per week, since a pound of fat is roughly 3,500 calories. Our example would target ~1,450. More on why this works in the calorie deficit guide, and the calorie deficit calculator sets the number for a target date.

  • Gain muscle: eat above TDEE — a modest surplus of 250–500 cal/day supports growth without excessive fat gain.

  • Maintain: eat at TDEE.

Don't go too aggressive. Cutting far below your BMR is counterproductive — energy, training quality, and muscle retention all suffer. A deficit that leaves you at or above BMR is almost always the smarter play.

Why the same person needs different numbers over time

TDEE isn't fixed. It drops as you lose weight (a smaller body burns less), rises as you add muscle, and shifts with activity. Recalculate every few kilograms of change rather than trusting a number from six months ago. And remember the multipliers are estimates — if the scale isn't moving the way the math predicts after 2–3 weeks, adjust intake by 100–150 calories and reassess rather than assuming the formula is broken.

Calories are the frame, not the whole picture

Hitting your calorie target drives weight change, but what those calories are made of drives how you look and feel. Protein in particular protects muscle in a deficit and keeps you full — see how much protein you actually need, then split the rest with the macro calculator.

The bottom line

Ignore the label. Your calorie target is your TDEE — your BMR scaled by how much you move — nudged up or down depending on your goal. Calculate it once with the TDEE calculator, subtract for fat loss or add for muscle, and recheck it every few kilos. It's the single most useful number in nutrition, and it takes under a minute to find.