Energy · free tool
Calorie Deficit Calculator
What a goal weight by a certain date actually asks of you, every day.
Your result
What a goal weight by a certain date actually asks of you, every day. Fill in the boxes and press Calculate — nothing is sent anywhere and no account is needed.
How this is worked out
- Total change = current weight − goal weight.
- Weekly rate = total change ÷ weeks.
- Daily deficit = weekly rate × 7,700 kcal per kg ÷ 7.
- A request is called aggressive above 1% of body weight a week, above a 1,000 kcal daily deficit, or above 0.5% a week when gaining. The alternative is drawn at 0.75% a week.
Sources
- Hall et al. (2011) on why the 7,700 kcal-per-kilogram rule overstates long-run loss: energy expenditure falls as body mass does, so a fixed deficit slows down rather than running in a straight line. PMID 21872751
These are population equations. They describe averages well and individuals only roughly — which is what makes them a starting point rather than a prescription. Nothing here is medical advice.
The thinking
Why an aggressive answer is never given quietly
Why an aggressive answer is never given quietly
Enter a big enough goal and a short enough timeframe and any calculator will return a number. Most of them do, without comment. The number is arithmetically correct and, as a plan, it is a way to lose muscle, feel terrible, and end the year heavier than you started.
So when the request is aggressive this page says so in plain words and shows a slower version of the same goal beside it — the same destination, a realistic date. You are welcome to ignore it. You will not be handed it without being told.
Questions
Straight answers.
- What is a sensible rate?
- Roughly 0.5–1% of your body weight a week for fat loss, and about 0.25–0.5% a week when gaining. Leaner people should sit at the slower end of both.
- Why does the estimate slow down over time?
- A smaller body costs less to run, and moving it burns less. The same daily deficit therefore produces less change in month three than in month one. This is expected, not failure.
- Should I just eat less and less?
- No. Longer beats lower, almost every time. If the number here looks impossible, change the timeframe rather than the food.
Keep going
One number is a reading. A trend is progress.
Every calculator here gives you a starting point and nothing more. What turns it into something useful is logging what you actually do against it — which is free, takes a minute a day, and is where the 14-day START HERE challenge begins.
Start freeNo card, no plan. Or see what coaching adds.