Calculator
Calorie deficit
How much to eat, how big the deficit has to be, and when you would get there. Worked out in your browser — nothing is sent anywhere.
2,000kcal
- Maintenance
- —
- Daily deficit
- —
- Total to burn
- —
- Time to goal
- —
- Target date
- —
Split this into protein, carbs and fat →
Based on roughly 7,700 kcal per kilogram of body fat. Real progress runs slower than the arithmetic — your maintenance falls as you get lighter, and incidental movement tends to drop during a deficit.
What the numbers mean
A calorie deficit is the gap between what you burn and what you eat. Your burn — maintenance — comes from the Mifflin–St Jeor equation plus an activity factor. Subtract your chosen pace and you get a daily intake target.
Put the same details into a different tool and you may well get a different answer — here is why they disagree, and which number to trust.
The timeline uses the standard conversion of roughly 7,700 kcal per kilogram of body fat, so 10 kg is about 77,000 kcal of accumulated deficit.Where that figure comes from, and why it is an approximation rather than a constant.
Picking a pace
Half a kilogram a week suits most people. Faster is possible and usually counterproductive: aggressive deficits cost more lean tissue, make training feel miserable, and — the thing that actually decides outcomes — are much harder to stay on. A 500 kcal deficit held for five months beats a 1,000 kcal deficit abandoned in three weeks.
Why reality runs slower than this table covers the drift you should expect.
Tracking it afterwards
A target calculated today is worth less each week, because every input moves. Caldown exists for that part: it turns the goal into a countdown that ticks down live from Apple Health, and recomputes the finish date from your real average deficit rather than the figure you typed at the start.