Weight Loss Calculator
See how long it takes to reach your goal weight.
Your result
Enter your details and press calculate to see your result.
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A weight loss calculator estimates how long it will take to reach a goal weight at a chosen daily calorie deficit. You enter your current weight, your target weight and how big a deficit you want to run, and it returns the weeks to your goal plus a week-by-week projection of where the scale should land. It turns a vague intention like lose 10 kilograms into a concrete timeline, so you can see whether your target date is realistic before you start.
How the timeline is calculated
The math rests on a single well-established figure: roughly 7,700 calories of energy are stored in one kilogram of body fat (about 3,500 calories per pound). So a daily deficit, multiplied by seven, then divided by 7,700, gives your expected weekly fat loss. The calculator divides the total weight you want to lose by that weekly rate to get the number of weeks.
For example, a 500-calorie daily deficit comes to 3,500 calories a week, which is 3,500 divided by 7,700, or about 0.45 kilograms per week. To lose 10 kilograms at that pace takes roughly 22 weeks, a little over five months. Run a larger 750-calorie deficit and the weekly loss climbs to about 0.68 kilograms, cutting the same goal to around 15 weeks.
Choosing a safe deficit
A 500-calorie deficit, near half a kilogram per week, is the popular middle ground because it is large enough to show steady progress but small enough to stay consistent and protect muscle. A common guideline is to lose about 0.5 to 1 percent of your bodyweight per week; faster than that and you risk losing muscle, feeling drained and rebounding once the diet ends.
To turn the deficit into a daily food target, subtract it from your maintenance calories (your TDEE). If your maintenance is 2,500 calories, a 500-calorie deficit means eating about 2,000 a day. Pair that with enough protein and resistance training so the weight you lose comes mostly from fat rather than muscle.
Why real loss is bumpier than the line
The projection is a straight-line model, but bodies do not cooperate that neatly. As you get lighter, your body burns fewer calories, so a fixed deficit produces slower loss over time and the trend gradually flattens. Day to day, water retention, food weight and hormones swing the scale by a kilogram or more in either direction. Weigh yourself on the same schedule, judge progress by the multi-week average rather than any single morning, and recalculate your deficit after every few kilograms so the plan keeps pace with your shrinking maintenance needs.
How to use
- 01
Enter current & goal weight
Add where you are now and where you want to be.
- 02
Choose a deficit
Pick how aggressive your daily calorie deficit will be.
- 03
See your timeline
Read the weeks to your goal and a weekly weight projection.
Frequently Asked Questions
About 0.5–1% of bodyweight per week is sustainable and protects muscle. Faster loss risks muscle and rebound.
As you lose weight your calorie needs fall, so a fixed deficit produces slower loss over time — recalculate periodically.
No — it is a model. Water weight, adherence and metabolism cause week-to-week variation around the trend.
A 500 kcal/day deficit (about 0.5 kg/week) is a popular, sustainable middle ground for most people.
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Last reviewed June 2026 · Methodology & sources