Calorie Deficit Calculator

A 20% deficit on a 2,500 kcal TDEE = 500 kcal/day — about 1lb/week loss.

Use the X% of Y calculator with deficit % and TDEE. 1lb fat ≈ 3,500 kcal; 500 kcal/day deficit ≈ 1lb/week.

Worked examples

2,500 kcal TDEE × 20% = 500 kcal deficit = ~1 lb/week loss.

2,800 kcal TDEE × 10% = 280 kcal deficit = ~0.5 lb/week loss.

Sources: NHS healthy weight loss · retrieved 2026-05-12.

Frequently asked questions

Can I just cut harder?

Aggressive deficits (>25-30%) accelerate muscle loss and are less sustainable. NHS guidance suggests 0.5-1kg per week as healthy.