Weight Loss Goal Date Calculator (diet D-day from your calorie deficit)

How it works

Days needed = kg to lose × 7,700 kcal ÷ daily deficit. The 7,700 kcal per kg figure is the classic rule (3,500 kcal per pound) for the energy stored in body fat. It is a first estimate only: as you lose weight your body burns less, so real loss usually slows and the true date tends to come later than this static rule predicts. Weekly loss = deficit × 7 ÷ 7,700.

⚠ This is not a diagnosis — talk to a doctor about your results.

FAQ

Why might I reach my goal later than this date?

The 7,700 kcal rule assumes a fixed deficit. When you lose weight your energy use drops, so the same diet makes a smaller deficit over time, and water shifts make the scale go up and down from day to day.

How big a deficit is sensible?

A deficit of about 500 kcal a day (about 0.5 kg a week) is a common, sustainable starting point. Very low-calorie diets should only be done with medical supervision.

Checked 11 Nov 2026. Wishnofsky M., “Caloric equivalents of gained or lost weight”, American Journal of Clinical Nutrition 6 (1958): 542–546 (≈3,500 kcal per lb); limitations: Hall K. D. et al., “Quantification of the effect of energy imbalance on bodyweight”, The Lancet 378 (2011): 826–837.