Fat Loss Calculator
Weight Loss Date Calculator works out Weight to lose and Daily calorie deficit from Current weight, Goal weight and Weight unit. The default figures on this page give goal date of 2027-02-01; change any entry and the result, the working and the sources update together.
Your figures
Updates as you typeHow this is worked out
5 steps
- Weight to lose = 200 - 180 = 20 lb (20 lb).
- Total energy deficit = 20 lb x 3500 kcal/lb = 70000 kcal.
- A 500 kcal daily deficit is 500 x 7 / 3500 = 1 lb per week.
- Time = 70000 / 500 = 140 days = 20 weeks.
- Counting 140 days from 2026-09-14 gives 2027-02-01.
Its 4 worked examples are re-run on every release, last on 15 September 2026. What changed
Sources and references
4 sources
Keep this result
Save it, change one figure, then compare the two
The calculation stays free. Save this scenario, adjust one assumption, save that too, and put them side by side to see exactly what the change costs you. A free account keeps 5 scenarios and 2 comparisons; Personal makes both unlimited and adds exports and private links. Nothing is saved unless you press Save.
What the Weight Loss Date Calculator calculates
Works out how many weeks a goal weight takes at a chosen daily calorie deficit or weekly loss rate, and the calendar date it is reached.
How to use this Weight Loss Date Calculator
Enter Current weight, Goal weight, Weight unit and Set the pace by. Weight to lose updates as you type, and “Use a worked example” loads checked figures you can adjust. Change one figure at a time to see what drives the result.
How the result is worked out
Open “How this is worked out” beside the result for the step-by-step calculation behind Weight to lose, Daily calorie deficit and Weekly loss rate.
The method follows CDC, Losing Weight - 1 to 2 pounds per week is the recommended rate, Wishnofsky M., Caloric equivalents of gained or lost weight, American Journal of Clinical Nutrition 6(5):542-546 - the 3,500 kcal per pound rule, Hall K.D. et al., Quantification of the effect of energy imbalance on bodyweight, The Lancet 378:826-837 - why the static 3,500 kcal rule overstates long-term loss and NIH Body Weight Planner, dynamic alternative to the static rule.
200 lb to 180 lb on a 500 kcal daily deficit example
With Current weight: 200, Goal weight: 180, Weight unit: lb, Daily calorie deficit: 500, the calculator returns Weight to lose: 20, Total energy deficit: 70000, Days to goal: 140. This example is checked against an independent source in the test suite.
What you can compare
Change one input at a time to see how it affects Weight to lose, Daily calorie deficit and Weekly loss rate. The inputs you can vary are Current weight, Goal weight, Weight unit, Set the pace by, Daily calorie deficit and Weekly loss rate.
Understanding Weight to lose, Daily calorie deficit and Weekly loss rate
This is an energy-balance projection, not a medical prediction. Real weight change deviates from it because energy expenditure falls as body mass falls. Anyone who is pregnant, under 18, or managing an eating disorder, diabetes or any other condition should set weight goals with a physician or registered dietitian.
Results are general information, not financial, tax, legal, medical or engineering advice. Check any decision that matters with a qualified professional.
See something wrong? Report a problem with this calculator
Frequently asked questions
How do I calculate how much fat I need to lose weight?
Works out how many weeks a goal weight takes at a chosen daily calorie deficit or weekly loss rate, and the calendar date it is reached. Open “How this is worked out” beside the result to see each step for your own figures.
What is the 3-3-3 rule for fat loss?
On the figures this page opens with — current weight 200, goal weight 180, daily calorie deficit 500 kcal/day and maintenance calories 2,400 kcal/day — the goal date is 2027-02-01. No single number fits everyone: change any figure above and the answer updates as you type, with each step of the arithmetic beside it.
How to lose 10 pounds in 2 months calculator?
It needs Current weight, Goal weight, Weight unit, Set the pace by, Daily calorie deficit and Weekly loss rate. Nothing else is required, and the figures stay in your browser.
How do I calculate how much body fat I've lost?
The result gives Weight to lose, Daily calorie deficit, Weekly loss rate, Monthly loss rate, Days to goal and Weeks to goal, each labelled with its unit so the figure can be read on its own.
What information do I need for the Weight Loss Date Calculator?
You need Current weight, Goal weight, Weight unit, Set the pace by, Daily calorie deficit, Weekly loss rate, Start date and Maintenance calories. The page opens with default figures that give goal date of 2027-02-01, so you can see the scale before entering your own.
What does this Weight Loss Date Calculator show?
It shows Weight to lose, Daily calorie deficit, Weekly loss rate, Monthly loss rate, Days to goal, Weeks to goal, Months to goal and Goal date, with the working and any warnings for your entries.