Calorie Deficit Calculator
Find the daily calorie target to hit your weekly weight-loss goal, based on your maintenance calories and the energy stored in body fat.
Last updated: June 20, 2026 · Medically reviewed by TG we-Calculate Editorial Teamkcal/day
kg/week
Goal unit
Estimate based on the 7,700 kcal/kg (3,500 kcal/lb) fat-energy rule.
- 1
Weekly energy deficit
0.5 kg × 7,700 kcal/kg = 3,850 - 2
Daily deficit
3,850 ÷ 7 = 550 - 3
Daily calorie target
2,200 − 550 = 1,650
How do I calculate my calorie deficit for weight loss?
Multiply your weekly weight-loss goal by the energy in body fat (about 7,700 kcal per kg or 3,500 kcal per lb), divide by 7 for the daily deficit, then subtract that from your maintenance calories (TDEE). The result is the daily intake to reach your goal — keep it at or above 1,200 kcal.
Formula
How this is calculated
You give two numbers: your maintenance calories (TDEE) — the kcal/day that keeps your weight steady — and how much weight you want to lose each week (kg or lb). The unit selector only changes which fat-energy constant is used.
The calculator converts your weekly goal into energy using the Wishnofsky rule: each kilogram of body-fat tissue stores about 7,700 kcal, each pound about 3,500 kcal. It multiplies your weekly goal by that constant to get the energy you must skip over a week, then divides by 7 to get the daily deficit. Subtracting that deficit from your TDEE gives the daily calorie target to eat.
For safety the target is floored at 1,200 kcal/day: if your goal would push intake below that, the result is clamped and a warning is shown. The model is purely linear — it assumes a fixed energy cost per unit of fat and a constant TDEE, so it ignores metabolic adaptation, water-weight swings, and changing maintenance needs. Real loss usually runs a bit slower than predicted, so treat the figure as a planning estimate rather than a guarantee.
Examples
| Input | Result |
|---|---|
| TDEE 2,200 kcal, lose 0.5 kg/week | Daily target ≈ 1,650 kcal (550 kcal/day deficit) |
| TDEE 2,500 kcal, lose 1 lb/week | Daily target ≈ 2,000 kcal (500 kcal/day deficit) |
| TDEE 1,600 kcal, lose 1 kg/week | Goal too aggressive — target floored at 1,200 kcal |
About this calculator
A calorie deficit means eating fewer calories than your body burns, which forces it to draw on stored energy and lose weight. This calculator uses the long-standing Wishnofsky "3,500 kcal per pound" rule (about 7,700 kcal per kilogram) to convert a weekly weight-loss goal into a daily energy deficit, then subtracts that deficit from your maintenance calories (TDEE) to give a daily intake target.
The rule is a useful planning estimate, not an exact prediction. Real weight loss slows over time as your body adapts and your maintenance need falls, so most people lose a little less than a simple linear model suggests. A common guideline is to aim for 0.25–1 kg (0.5–2 lb) of loss per week, and to keep daily intake at or above roughly 1,200 kcal for women and 1,500 kcal for men unless supervised by a clinician. This tool floors the target at 1,200 kcal and warns when your goal is too aggressive.
Frequently asked questions
A deficit of 500–750 kcal per day, giving about 0.5–0.75 kg (1–1.5 lb) of loss per week, is widely considered safe and sustainable for most adults. Keep daily intake at or above 1,200 kcal unless supervised by a clinician.
The 3,500 kcal rule assumes a fixed energy cost per kilogram. In practice your metabolism adapts and your maintenance need drops as you lose weight, so loss tapers off and is usually a bit less than the linear estimate.
It is an approximation. Body-fat tissue is not pure fat, so the figure of roughly 7,700 kcal per kg (3,500 kcal per lb) is a planning estimate rather than an exact constant.
Also known as
Sources & references
TG we-Calculate Editorial Team. (2026). Calorie Deficit Calculator [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/calorie-deficit-calculator
TG we-Calculate Editorial Team. "Calorie Deficit Calculator." TG we-Calculate. 2026. https://we-calculate.com/calculator/calorie-deficit-calculator.
TG we-Calculate Editorial Team, "Calorie Deficit Calculator," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/calorie-deficit-calculator
@misc{wecalculate_calorie_deficit_calculator, title = {Calorie Deficit Calculator}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/calorie-deficit-calculator}}, year = {2026}, note = {TG we-Calculate} }
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