Weight Loss Calculator
Project how long it will take to reach your target weight from your daily calorie deficit, with weekly loss rate and estimated goal date.
About the Weight Loss Calculator
This weight loss calculator projects your journey from current weight to target weight based on your planned daily calorie deficit. It converts the deficit into a weekly loss rate, estimates the total number of weeks required, and pins an approximate goal date on the calendar.
The projection uses the standard approximation that one kilogram of body fat stores about 7,700 kcal, so a 500 kcal daily deficit works out to roughly 0.45 kg per week. Sustainable plans usually target 0.25–1 kg per week; the calculator warns you when your chosen deficit implies a faster, harder-to-sustain pace.
Real-world loss is not perfectly linear — water weight moves fast in the first weeks, and metabolism adapts as you get lighter, so late progress is slower than the straight-line estimate. Pair this tool with our calorie calculator to find your maintenance calories first, then choose a deficit you can actually live with.
How to Use the Weight Loss Calculator
- 1Enter your current weight and target weight in kilograms.
- 2Enter your planned daily calorie deficit (calories below maintenance).
- 3Read the projected weekly loss, total weeks and estimated goal date.
- 4Adjust the deficit to find a pace between 0.25 and 1 kg per week.
Frequently Asked Questions
How long will it take to lose 10 kg? A worked example
With a 500 kcal daily deficit: weekly loss = 500 × 7 ÷ 7,700 ≈ 0.45 kg, so 10 kg takes about 22 weeks — roughly five months. Doubling the deficit to 1,000 kcal halves it to about 11 weeks, but that pace is hard to sustain and often not advisable.
Where does the 7,700 kcal per kg figure come from?
Body fat tissue stores roughly 7,700 kcal per kilogram (the well-known 3,500 kcal per pound rule). It's a useful planning approximation, though real loss includes some water and lean mass and metabolism adapts over time, so actual progress usually runs somewhat slower than the formula in later months.
What is a safe rate of weight loss?
Most guidelines recommend 0.25–1 kg (0.5–2 lb) per week. Faster loss increases the share of muscle lost, risks nutritional gaps, and correlates with rebound weight gain. This calculator flags any plan exceeding 1 kg per week.
How do I know my calorie deficit?
First find your maintenance calories (TDEE) with a calorie calculator — for example 2,400 kcal per day. Eating 1,900 kcal gives a 500 kcal deficit. Exercise adds to the deficit too: a 300 kcal workout on top of that diet makes the day's total deficit about 800 kcal.
Why did my weight loss stall even though I kept the same deficit?
As you lose weight your body burns fewer calories at rest and during movement, so yesterday's deficit shrinks. Recalculate your TDEE every 5 kg or so and adjust intake, and expect week-to-week noise from water and glycogen shifts — judge trends over 2–3 weeks, not days.