What this calculator measures
A calorie deficit means consuming fewer calories than your body burns in a day. This is the fundamental driver of fat loss — regardless of the specific foods you eat. The size of the deficit determines how fast you lose weight, and how much muscle you can retain during the process.
How this calculator works
Your target calories equal your maintenance intake (TDEE) minus your chosen deficit percentage. Estimated weekly weight loss uses 7,700 kcal ≈ 1 kg as a planning conversion (based on the 3,500 kcal/lb convention adapted to metric). Actual rate will vary due to water retention, glycogen changes, and individual metabolic variation.
How to use your result
A deficit of 10–20% is appropriate for most people, targeting about 0.25–0.5 kg of fat loss per week. Larger deficits can accelerate loss but increase the risk of muscle loss, performance drops, and poor adherence. Combine this with the protein calculator to maintain adequate protein intake — which is the primary nutritional defence against muscle loss in a deficit.
Important limitation
Calculator results are estimates. Pregnancy, eating disorders, medical conditions, injuries, or concerning symptoms require qualified professional guidance.