Weight Loss Calculator
Weight loss is arithmetic with a timetable: a set number of kilos, a weekly rate and therefore an approximate finish date. This calculator turns those three variables into each other, showing how many weeks a goal needs at a chosen pace and what daily calorie deficit that pace demands.
Enter values
Results
- Time to goal
- 16 weeks
- Weight to lose
- 8 kg
- Daily calorie deficit needed
- 550 kcal/day
- Goal date
- 7 Feb 2027
How is the Weight Loss calculated?
Start with the gap between your current and target weight. Dividing it by your chosen weekly rate gives the number of weeks required, which assumes the rate holds steady throughout. To translate that weekly pace into food, the calculator uses the classic figure of seven thousand seven hundred kilocalories per kilogram of body fat: multiply your weekly loss by that constant for the weekly energy deficit, then divide by seven for the daily cut you need from diet, exercise or both.
Formula
Kilograms to lose = current − target. Weeks = kilograms ÷ weekly rate. Daily deficit = (weekly rate × 7700) ÷ 7 kcal/day, where 7700 kcal corresponds to one kilogram of body fat.
Example
Going from 80 kg to 72 kg at half a kilo a week means losing 8 kg, so 8 ÷ 0.5 = 16 weeks, roughly four months of steady effort. The daily deficit behind that pace is 0.5 × 7700 ÷ 7 ≈ 550 kcal a day. The same 8 kg at a quarter kilo a week stretches to 32 weeks but needs only about 275 kcal a day, while a full kilo weekly halves the timeline to eight weeks and demands close to 1100 kcal daily.
Things to remember
Set the rate that matches your life rather than your impatience, expect the pace to wobble with water weight and holidays, and judge progress on the monthly average. The finish line moves closer with every week the trend keeps falling.
Frequently Asked Questions
How many calories are in a kilogram of body fat?
The standard figure is seven thousand seven hundred kilocalories, which this calculator uses to convert a weekly loss into a daily deficit. Real fat loss also includes some lean tissue and water, so dietitians keep seven thousand seven hundred as the conservative working number.
What is a safe weekly weight loss rate?
Half a kilo per week suits most people, while a quarter kilo is gentle and one kilo is ambitious but achievable at higher starting weights. Faster rates raise the risk of losing muscle, gallstones and energy crashes.
Why is the scale not moving even with a deficit?
Water retention from new training, salt, carbohydrates or menstrual cycles can hide fat loss for a couple of weeks, especially early on. Track a weekly average over a month before changing anything, because daily readings bounce by more than the deficit you are running.
Should I combine diet and exercise for the deficit?
Splitting the gap feels easier than taking it all from food: a five hundred calorie cut changes your plate, while the same amount through walking adds an hour of steps. Most people take most of the deficit from diet and top it up with activity they can repeat.
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