Calculate how many weeks it takes to reach your goal weight, based on your current weight and a daily calorie deficit.
One kilogram of body fat corresponds to roughly 7,700 kcal. The calculator uses this ratio to work out how long it takes to reach your goal weight with a given daily calorie deficit:
If you have 7 kg to lose and maintain a deficit of 500 kcal per day, the math gives 7 × 7,700 ÷ 500 ≈ 108 days, or roughly 15.4 weeks. In practice, weight loss is rarely perfectly linear — the body responds differently week to week, and factors like fluid balance, muscle mass and metabolism also play a role.
3,500 kcal is a commonly used approximation for the energy content of one pound of body fat. It's an average figure — actual energy needs vary from person to person and often change during a weight loss period.
A deficit of 300–500 kcal per day normally gives a weight loss of around 0.5–1 kg (1-2 lb) per week, considered a healthy pace by most health authorities. Larger deficits can give faster results, but increase the risk of muscle loss and weight regain.
The body isn't a perfect calculator. Fluid retention, hormonal fluctuations, sleep, stress and changes in muscle mass mean actual weight loss rarely follows a straight line, even with a constant calorie deficit over time.