About the Calorie Deficit Calculator
A calorie deficit means eating fewer calories than your body burns. This calculator works backwards from a goal: enter your current weight, goal weight, how many weeks you want to take and your maintenance calories (TDEE), and it tells you the daily deficit, the daily calorie intake that creates it, the weekly rate of loss and the date you would reach your goal.
It is useful when you have a deadline — an event, a weigh-in or a health check — and want to know whether it is realistic. The pace table compares common rates (0.5 to 2 lb, or 0.25 to 1 kg, per week) so you can see how much sooner a larger deficit gets you there and what it costs in daily calories.
The math uses the rule of thumb that about 3,500 kcal of deficit equals one pound of body weight (7,700 kcal per kilogram). That is a good first estimate, but actual loss usually slows over time as maintenance calories fall, so build in some buffer and recalculate as you go. If you do not know your TDEE, get it from the TDEE calculator first.
With the default inputs, the daily calorie intake is 2,000 kcal/day. Change any value above to recalculate instantly.
How to use the calorie deficit calculator
- 1Choose US or metric units.
- 2Enter your current weight and your goal weight.
- 3Enter your maintenance calories (TDEE) — use the TDEE calculator if unsure.
- 4Set how many weeks you want to take and your start date.
- 5Read your daily calorie target and check the pace table for a safer or faster option.
Formula and method
The calculator converts the weight you want to lose into an energy deficit using the widely used approximation that one pound of body weight corresponds to about 3,500 kcal (7,700 kcal per kilogram). Spreading that total over your chosen number of days gives the required daily deficit, and subtracting it from your maintenance calories gives the intake to aim for.
This static rule assumes your maintenance calories stay constant. In reality they fall as you lose weight, so the same intake produces slower loss over time. For long diets, recalculate your TDEE every few weeks or use the weight loss calculator, which models that slowdown.
- TDEE
- Total daily energy expenditure (maintenance calories)
- 3,500 / 7,700
- Approximate kcal per lb / per kg of body weight
Worked examples
Lose 20 lb in 20 weeks with a 2,500 kcal TDEE
20 lb × 3,500 kcal = 70,000 kcal. Spread over 140 days that is a 500 kcal daily deficit, so eating 2,000 kcal a day loses about 1 lb a week. Starting on 5 January 2026, the goal date is 25 May 2026.
Metric: 95 kg to 85 kg in 16 weeks, TDEE 2,800 kcal
Losing 10 kg needs about 10 × 7,700 = 77,000 kcal. Over 112 days that is a 687.5 kcal daily deficit, so the target intake is about 2,113 kcal a day for roughly 0.63 kg of loss per week.
Aggressive: 180 lb to 160 lb in 10 weeks, TDEE 2,200 kcal
Losing 20 lb in 70 days needs a 1,000 kcal daily deficit — 45% of maintenance — leaving only 1,200 kcal a day. That is 2 lb a week, over 1% of body weight weekly, so a longer timeline would be more sustainable.
Frequently asked questions
How big should my calorie deficit be?+
A deficit of about 300–500 kcal a day, or 10–25% of your maintenance calories, suits most people. It typically produces 0.5–1 lb (0.25–0.5 kg) of loss a week while keeping hunger, fatigue and muscle loss manageable.
How many calories is 1 pound of fat?+
The common approximation is 3,500 kcal per pound, or about 7,700 kcal per kilogram. Body fat tissue actually contains a little water and protein, and early weight loss includes water, so treat it as an estimate rather than an exact conversion.
Why am I not losing weight in a calorie deficit?+
Usually the deficit is smaller than planned: intake is underestimated or activity overestimated. Water retention can also hide fat loss for a week or two. Compare weekly average weights over at least 3 weeks before changing your plan.
Is a 1,000 calorie deficit safe?+
For people with a lot of weight to lose it can be acceptable short-term, but for most it is aggressive: it raises the risk of muscle loss, nutrient shortfalls and rebound eating. Keep intake above about 1,200–1,500 kcal unless supervised by a clinician.
Can I create a deficit with exercise instead of eating less?+
Yes — a deficit is simply burning more than you eat. Most people find it easier to combine a modest intake reduction with more activity, since exercise alone burns fewer calories than many expect.
This tool gives general estimates and is not medical advice. Talk to a doctor or qualified professional about your health, diet or training.
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