What TDEE actually means
TDEE is the total amount of energy, measured in calories, that your body uses over 24 hours. It bundles together everything: keeping you alive at rest, digesting your food, walking to the kitchen, and whatever training you do. It's the single most useful number in nutrition because it's the line you eat above or below to change your weight.
Every TDEE calculation is built from two pieces. First you estimate your BMR — the calories you'd burn lying in bed all day doing nothing. Then you multiply that by an activity factor that accounts for movement and exercise. That's the whole method.
Step 1 — Estimate your BMR
The most reliable formula in everyday use is the Mifflin-St Jeor equation. It's the modern standard, more accurate for most people than the older Harris-Benedict equation. There's one version for each sex, differing only in the final constant.
Women: BMR = (10 × weight kg) + (6.25 × height cm) − (5 × age) − 161 Mifflin-St Jeor equation — weight in kilograms, height in centimetres, age in years
If you think in imperial units, convert first: 1 lb is 0.45 kg, and 1 inch is 2.54 cm. Height in feet and inches becomes total inches first, then centimetres.
Step 2 — Apply your activity multiplier
BMR is only the resting figure. To reach TDEE you multiply it by a factor that reflects how much you move. Be honest here — this is where most people overestimate. "Moderately active" means genuine, structured exercise several times a week, not a busy day at the office.
| Activity level | Multiplier | Who it fits |
|---|---|---|
| Sedentary | × 1.2 | Desk job, little or no exercise |
| Lightly active | × 1.375 | Light exercise 1–3 days/week |
| Moderately active | × 1.55 | Moderate exercise 3–5 days/week |
| Very active | × 1.725 | Hard exercise 6–7 days/week |
| Extra active | × 1.9 | Physical job or twice-daily training |
A worked example
Take a 32-year-old woman, 5 ft 6 in tall, weighing 150 lb, who lifts weights and runs four days a week (moderately active).
BMR: (10 × 68) + (6.25 × 168) − (5 × 32) − 161 = 680 + 1,050 − 160 − 161 = 1,409 calories.
TDEE: 1,409 × 1.55 = ≈ 2,184 calories. That's roughly what she burns in a full day, and the number she eats to maintain her weight.
Turning TDEE into a goal
Once you have your maintenance number, adjusting your weight is straightforward. A pound of body fat is about 3,500 calories, so a daily deficit of 500 calories predicts roughly 1 lb of fat loss per week. The same logic runs in reverse for gaining.
- Lose fat. Subtract 10–20% from your TDEE. A moderate deficit protects muscle and is easier to sustain than a crash diet.
- Maintain. Eat at your TDEE. Weight holding steady over 2–3 weeks confirms your estimate is accurate.
- Gain muscle. Add 5–15% above your TDEE. A small surplus paired with resistance training favours lean mass over fat.
- Recheck monthly. As your weight changes, so does your BMR. Recalculate every few weeks to keep the target honest.
Why your TDEE is an estimate, not a law
Every equation produces a prediction, not a guarantee. Two people with identical stats can differ by a few hundred calories a day thanks to genetics, muscle mass, hormones, and how much they fidget. The formula gets you a strong starting point; your own results over a few weeks are the real calibration. If the scale isn't moving the way the math predicts, adjust your intake by 100–200 calories and give it another two weeks.
Frequently asked questions
Is TDEE the same as maintenance calories?
Yes. Your TDEE is the number of calories that keeps your weight stable, which is exactly what "maintenance calories" means. Eat above it to gain, below it to lose.
How is TDEE different from BMR?
BMR is only what your body burns at complete rest. TDEE is BMR plus all the energy you spend moving, exercising, and digesting food. TDEE is always the larger number.
Should I eat back the calories I burn during exercise?
Not if you used an activity multiplier to calculate your TDEE — that exercise is already baked into the number. Eating it back a second time double-counts it and can stall fat loss.
How often should I recalculate?
Every time your weight shifts by about 10 lb, or roughly once a month during an active cut or bulk. A lighter body burns fewer calories, so an old TDEE slowly becomes wrong.