Losing half a kilo a week needs a deficit of about 550 kcal a day. Set your target weight and pace, and see the daily calories and the finish date it implies.
Daily calorie target
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Daily calorie target—
Your current expenditure—
Daily deficit—
Kilos to lose—
Estimated time—
Approximate date—
Check—
How this was worked out
Indicative result. A sustained deficit below your basal metabolic rate costs muscle and slows your metabolism. If the result falls below it, the calculator says so.
The formula
target = TDEE − (weekly rate × 7,700 ÷ 7)
Where it comes from
A kilogram of body fat stores roughly 7,700 kcal, so the arithmetic of a deficit is straightforward: pick a weekly rate, convert it to a daily shortfall, and subtract it from what you burn. What is not straightforward is that your expenditure falls as you lose weight, so the same intake produces a smaller deficit over time.
How to work it out by hand
Work out your total daily expenditure
Multiply your weekly target rate by 7,700 kcal
Divide by seven for the daily deficit
Subtract it from your expenditure for the daily calorie target
What is worth knowing
Two things this arithmetic hides. Your expenditure falls as you get lighter — you are carrying less around — so a deficit that worked at the start shrinks by itself, and the calculation needs redoing every few kilos. And the 7,700 kcal figure assumes the loss is all fat, which it never quite is. The floor that matters is your basal rate: eating below it for any length of time costs lean mass and is difficult to do while meeting your protein and micronutrient needs. The calculator flags it when the target crosses that line.
Frequently asked questions
How big a deficit is safe?
Generally 15 to 25 % below your expenditure, and never sustained below your basal rate. That works out at roughly 0.5 to 1 % of body weight a week.
Why is my loss slowing down?
Because a lighter body burns less. Recalculate every three or four kilos, and expect the same intake to produce a smaller deficit over time.
Is 7,700 kcal per kilo accurate?
It is the standard figure for pure fat. Real weight loss includes water and some lean tissue, so early loss is usually faster than the arithmetic predicts.
Should I eat back exercise calories?
Not if your activity factor already accounts for the exercise. Doing both double-counts it and erases the deficit.
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