What the TDEE calculator does
The TDEE calculator estimates your Total Daily Energy Expenditure — the calories you burn in 24 hours, including basic metabolism, exercise, fidgeting, walking and digesting food. It is the single most useful number for setting calorie targets, because eating your TDEE keeps weight steady, eating below it produces fat loss, and eating above it produces gain. The page shows your chosen level prominently and an at-a-glance table of all five activity multipliers so you can compare without re-running the math.
How TDEE is calculated
Two steps:
- BMR (Mifflin-St Jeor): 10 × kg + 6.25 × cm − 5 × age + 5 (men) or − 161 (women).
- TDEE = BMR × activity factor.
The activity factors are: 1.2 sedentary, 1.375 lightly active, 1.55 moderately active, 1.725 very active, 1.9 athlete. These are widely used and reasonably accurate within about 10% for typical adults.
The honest activity level question
Almost everyone overestimates their activity level, and an overestimate is what makes fat-loss plans stall before they start. Here's a more honest mapping:
- Sedentary (1.2) — desk job, drive everywhere, no structured exercise.
- Lightly active (1.375) — desk job plus 1-3 workouts a week, or a job that has you on your feet but you don't train.
- Moderately active (1.55) — train 3-5 days a week and walk a fair bit during the day (10,000+ steps).
- Very active (1.725) — daily training plus a physically active lifestyle, or hard manual labour.
- Extra active (1.9) — competitive athlete or very physical job (construction, farm work, military training).
If you're choosing between two adjacent levels, pick the lower one. You can always add a hundred calories if the trend stalls.
TDEE vs. BMR vs. RMR
The three terms get used loosely but mean different things. BMR is calories at total rest in a lab. RMR (resting metabolic rate) is calories at rest in normal conditions — typically 10-20% higher than BMR. TDEE includes all activity. Most everyday calculators (this one included) report BMR but multiply it by activity factors that implicitly include the BMR-to-RMR difference.
Using TDEE in practice
For maintenance, eat your TDEE. For fat loss, subtract about 500 kcal (≈ 0.45 kg / 1 lb per week). For lean gain, add 300 kcal (≈ 0.25 kg / 0.5 lb per week). Track weekly average weight for 2-4 weeks and nudge by 100-150 kcal if the trend doesn't match the plan.
Use with the other tools
For just the BMR side, the BMR calculator compares Mifflin-St Jeor and Harris-Benedict. For a goal-adjusted calorie target, use the calorie calculator. For protein, carb and fat targets, the macro calculator picks those splits from the same engine.