How to use the TDEE Calculator
- Enter age, sex, height and weight to establish your resting rate.
- Choose the activity level that matches a typical week, not your best week.
- Read maintenance calories, then apply a deficit or surplus.
- Re-check the figure after four to six weeks of actual weight data.
How the calculation works
TDEE multiplies BMR by an activity factor, conventionally 1.2 for sedentary through to around 1.9 for very heavy physical work or daily hard training. Those factors bundle three separate things: deliberate exercise, non-exercise movement such as walking and fidgeting, and the thermic effect of food, which accounts for roughly 10% of intake.
The most common error is over-selecting the activity level. Three gym sessions a week in an otherwise desk-bound life is 'lightly active', not 'very active', and the difference between those two factors can be 400 calories a day — enough to turn an intended deficit into maintenance. Choose the lower option when in doubt and let observed weight change correct it.
TDEE = BMR × activity factor (1.2 sedentary, 1.375 light, 1.55 moderate, 1.725 very active, 1.9 extreme)Source: Physical activity level multipliers as used in FAO/WHO/UNU energy requirement reports, applied to a Mifflin-St Jeor BMR.
Worked example
A man with a BMR of 1,780, working a desk job, lifting weights three times a week.
- Activity level is light to moderate rather than very active: factor 1.375.
- TDEE = 1,780 × 1.375 = 2,447.5.
- For fat loss, subtract 500: 1,948 calories per day.
Maintenance ≈ 2,450 calories; a 500-calorie deficit target of about 1,950 should produce roughly 0.45 kg of loss a week.
Frequently asked questions
How large a deficit should I run?+
A deficit of 15 to 25% of TDEE — often 400 to 600 calories — is sustainable for most people and preserves muscle better than an aggressive cut. Very large deficits increase muscle loss and rarely survive contact with real life.
Should I eat back the calories from exercise?+
Not if your activity factor already includes that training. Doing so double-counts the same session, which is a frequent reason a carefully tracked deficit produces no weight change.
Why has my weight stopped falling on the same intake?+
A lighter body has a lower TDEE, and adaptive changes reduce spontaneous movement during a long deficit. Recalculate at your current weight and consider a maintenance break before cutting further.
How accurate is the activity multiplier?+
It is a broad bracket rather than a measurement. Treat the resulting TDEE as a hypothesis, track intake and weight for three weeks, and adjust by 100 to 200 calories based on what actually happened.
Last reviewed August 31, 2026. We review this page whenever the underlying formula, tax year, published rate or standard changes.