DeficitPlan

Calorie Deficit Calculator

3500 kcal ≈ 1 lb — project weight loss over any number of weeks.

TDEE (kcal)

Daily deficit (kcal)

Weeks

Daily calories: 2,000 kcal
Weekly loss (lb): 1
Weekly loss (kg): 0.45
Total loss (lb): 12

Standard rule: 3500 kcal ≈ 1 lb of fat.

What you entered

TDEE: 2500 kcalDaily deficit: 500 kcalDuration: 12 weeks

1
Daily calorie target
2500 − 500 kcal deficit= 2000 kcal/day
2
Weekly fat loss (3,500 kcal ≈ 1 lb)
(500 × 7) ÷ 3500= 1.00 lb/week
3
Total loss over 12 weeks
1.00 × 12= 12.0 lb

Result

Daily calorie target: 2,000 kcal

At this deficit, expect to lose about 12 lb over 12 weeks. Deficits much steeper than this risk muscle loss and rebound — a moderate, sustained deficit works better long-term than an aggressive one.

Weekly and 12-week fat loss at common daily calorie deficits

Worked from a 2,500 kcal TDEE using the standard 3,500 kcal per pound rule. The eat-per-day column is what you would actually eat; the loss columns project that deficit forward over a 12-week block.

Daily deficit (kcal)	Eat per day (kcal)	Loss per week (lb)	Loss per week (kg)	Loss over 12 weeks (lb)
200	2,300	0.40	0.18	4.8
250	2,250	0.50	0.23	6.0
300	2,200	0.60	0.27	7.2
400	2,100	0.80	0.36	9.6
500	2,000	1.00	0.45	12.0
750	1,750	1.50	0.68	18.0
1,000	1,500	2.00	0.91	24.0

Change the TDEE input and only the eat-per-day column shifts; the loss columns depend on the deficit alone. The 3,500 kcal per pound figure is a planning average, not a physiological constant, and real loss slows as you get lighter because your TDEE falls with your body weight, so recalculate every 10 to 15 lb. Deficits much beyond 750 kcal a day are hard to hold and cost lean mass. Illustrative estimates for planning, not medical advice.

Why 3,500 calories roughly equals a pound

A pound of body fat stores approximately 3,500 kcal of energy — so a consistent daily deficit of 500 kcal works out to about one pound lost per week, which is the arithmetic this calculator projects forward.

A useful estimate, not a guarantee

Real weight loss varies with water retention, muscle changes, and metabolic adaptation, so treat this as a reasonable planning estimate rather than a precise prediction.

Frequently asked questions

What calorie deficit do I need to lose 1 pound per week?

A deficit of 500 calories per day (3,500 per week). If your TDEE is 2,500 calories, eat 2,000. For 2 lbs/week, a 1,000 cal/day deficit is needed — but deficits this large are hard to sustain and risk muscle loss. Most experts recommend 500–750 cal/day (1–1.5 lbs/week) for sustainable fat loss.

Why does weight loss slow down over time?

Metabolic adaptation: as you lose weight, your body burns fewer calories (less mass to maintain, lower NEAT, hormonal changes). A 500-calorie deficit at 200 lbs becomes a 300-calorie deficit at 180 lbs if you don't recalculate. Recalculate your TDEE every 10–15 lbs lost and adjust intake.

Is a 1,200 calorie diet safe?

1,200 calories is the minimum generally recommended for women (1,500 for men) without medical supervision. Going below risks nutrient deficiencies, muscle loss, metabolic slowdown, and hormonal disruption. Very low calorie diets (<800 cal) should only be done under medical supervision. A moderate deficit (20–25% below TDEE) is safer and more sustainable.