How TDEE is calculated
TDEE starts with your basal metabolic rate — the calories you burn at rest, from the Mifflin-St Jeor equation — and multiplies it by an activity factor that reflects how much you move. The factors run from 1.2 for a sedentary lifestyle to 1.9 for someone with a physical job who also trains hard. The result is the calories you burn on an average day. It bundles together the three parts of expenditure: your resting metabolism, the energy used to digest food, and all your movement, from workouts to fidgeting.
Using TDEE to lose or gain weight
Weight change is calories in versus calories out. Eat at your TDEE and your weight holds steady. Eat about 500 calories below it and you lose roughly half a kilogram of fat a week, a sustainable rate that protects muscle. Eat 300–500 above it to gain slowly and lean. Bigger deficits speed loss but risk muscle and energy, so a moderate gap plus adequate protein and strength training is the reliable approach. This calculator shows the maintenance, cutting and bulking numbers side by side.
Picking the right activity level
The most common mistake is overstating activity. A few gym sessions a week is 'light' to 'moderate', not 'active'. Desk workers who train three or four times a week usually land around 1.375–1.55. Reserve 1.725 and 1.9 for manual jobs or two-a-day training. If your weight does not move as predicted after a couple of weeks, your true activity factor is probably lower than you picked — adjust down rather than slashing calories.
Why the number needs adjusting
TDEE is an estimate built on population averages, so use it as a starting budget and let the scale fine-tune it. Track your weight for two to three weeks at a set intake; if it is not moving the way the goal calories predict, nudge intake by 100–200 calories and reassess. These tools use standard, published formulas and the figures you enter. They are estimates for general fitness and planning, not a medical assessment — check with a doctor or dietitian before making health decisions.
Frequently asked questions
What is the difference between BMR and TDEE?
BMR is the calories you burn at rest. TDEE is BMR multiplied by an activity factor, so it includes movement and exercise. TDEE is the number you eat to maintain weight.
How many calories should I eat to lose weight?
Roughly 500 below your TDEE for about half a kilogram (one pound) of loss per week. This calculator shows that target automatically alongside maintenance.
Why am I not losing weight at my TDEE minus 500?
Usually the activity level was set too high, or intake is underestimated. Track carefully for two to three weeks and lower the activity factor or calories if the scale does not move.
How often should I recalculate TDEE?
Every few kilograms of weight change, since a lighter body burns fewer calories. Recalculating keeps your deficit or surplus accurate.