Calorie Deficit Calculator
Set a weight-loss target and see the daily calories and the date you would reach it.
How it works
daily deficit = (lb per week × 3500) ÷ 7 · intake = TDEE − deficit
The classic approximation: one pound of body fat stores roughly 3,500 kcal. It is imperfect (metabolism adapts, water weight moves) but works well for planning over weeks. The calculator flags targets under 1,200 kcal/day.
Worked example
With a 2,600-kcal TDEE, losing 1 lb/week needs a 500-kcal daily deficit — eating about 2,100 kcal/day. Fifteen pounds takes roughly 15 weeks.
Frequently asked questions
Is the 3,500-calorie rule exact?
No — it’s a planning approximation. Real loss slows over time as the body adapts and gets lighter. Re-run the numbers as you go.
Why did week one lose more than predicted?
Early loss includes water and stored carbohydrate (glycogen), not just fat. The trend from week 3 onward is the honest signal.
Faster is better, right?
Steep deficits cost more muscle, are harder to sustain, and rebound more often. 0.5–1% of body weight per week is the widely used sustainable range.
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This is a general educational estimate, not medical advice. Bodies differ — for decisions about diet, training, medication or health conditions, talk to a doctor or registered dietitian.