Calorie Deficit Calculator: How Many Calories to Lose Weight

How to calculate a calorie deficit

Deficit = maintenance calories (TDEE) − what you eat. One kilogram of body fat stores roughly 7,700 calories (about 3,500 per pound), so a 500-calorie daily deficit adds up to about 0.5 kg (1 lb) a week. The calculator estimates your TDEE, subtracts the deficit you choose and shows the resulting target.

How big a deficit is safe?

The CDC links gradual loss of 1–2 lb (0.5–1 kg) a week with keeping the weight off. That usually means a 500–1,000-calorie daily deficit — but never below about 1,200 calories for women or 1,500 for men without medical supervision, and never below your BMR for long. Smaller, steadier deficits preserve muscle and are easier to keep.

When will I reach my goal weight?

Divide the total you want to lose by your weekly rate. Losing 10 kg at 0.5 kg/week takes about 20 weeks. Expect the real timeline to be 10–20% longer: metabolism adapts and adherence is never perfect. Re-run the calculator every 5 kg (10 lb) so the deficit stays accurate.

Calorie deficit vs TDEE

TDEE is the baseline; the deficit is what you take off it. If you already eat close to your TDEE, weight is stable by definition — the deficit is created either by eating less, moving more, or both. Adding 30 minutes of brisk walking most days is worth roughly 100–150 calories for an average adult.

Sources

• CDC, Losing weight — https://www.cdc.gov/healthy-weight-growth/losing-weight/index.html
• Dietary Guidelines for Americans (current edition) — https://www.dietaryguidelines.gov/
• Mifflin-St Jeor equation, PubMed 2305711 — https://pubmed.ncbi.nlm.nih.gov/2305711/

This calculator is educational and not medical advice. If you have a health condition, are pregnant, or are under 18, ask a clinician before changing your diet.