Calorie Deficit Calculator
Katch-McArdle active — height & age not used.
Formula: Mifflin-St Jeor (Katch-McArdle when body fat % is given) × activity factor. Defaults shown are an example profile — replace them with yours. Every constant is documented on the methodology page. Educational estimate — not medical advice.
Pick a −10%, −20% or −25% deficit from your TDEE, with expected weekly loss.
Deficit targets by maintenance level
Daily intake targets in kcal/day. Find your maintenance (TDEE) with the calculator above, then read across. Method: deficit guardrails.
| Maintenance (TDEE) | Mild (−10%) | Standard (−20%) | Aggressive (−25%) |
|---|---|---|---|
| 1,800 kcal | 1,620 kcal | 1,440 kcal | 1,350 kcal |
| 2,000 kcal | 1,800 kcal | 1,600 kcal | 1,500 kcal |
| 2,200 kcal | 1,980 kcal | 1,760 kcal | 1,650 kcal |
| 2,400 kcal | 2,160 kcal | 1,920 kcal | 1,800 kcal |
| 2,600 kcal | 2,340 kcal | 2,080 kcal | 1,950 kcal |
| 2,800 kcal | 2,520 kcal | 2,240 kcal | 2,100 kcal |
| 3,000 kcal | 2,700 kcal | 2,400 kcal | 2,250 kcal |
| 3,200 kcal | 2,880 kcal | 2,560 kcal | 2,400 kcal |
How big should your calorie deficit be?
A pound of body fat stores roughly 3,500 kcal, so a 500 kcal daily deficit works out near one pound per week — that is the “standard” −20% row for most people. Milder deficits are slower but easier to sustain and kinder to training performance; aggressive cuts trade comfort and some muscle risk for speed and should be run for shorter blocks.
Two guardrails: the calculator flags any target that lands below your BMR, and very-low-calorie dieting belongs under professional supervision. Weigh in daily, average weekly, and judge the deficit by the trend — if weight stalls three weeks straight, drop another 100–150 kcal or add activity rather than slashing further in one jump.