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Calorie Deficit Calculator
Set a goal weight and a number of weeks, and this calculator works out the daily calorie deficit that would get you there and the intake that deficit leaves you with. It uses your TDEE from the Mifflin-St Jeor equation and the 3,500 kcal per pound rule.
- Daily deficit
- 500 kcal/day
- Maintenance calories (TDEE)
- 2,763 kcal/day
- Weight change per week
- 1 lb
- Check
- Within the 1–2 lb a week usually advised
Saved setups
Save a set of inputs you reuse — your usual rate, your loan, your room sizes — and load it back in one tap.
Your recent calculations
Results you calculate here are kept on this device so you can come back to them.
Formula
How to use it
- Enter your sex, age, height, current weight and activity level.
- Enter your goal weight and how many weeks you want to take.
- Read the daily deficit and calorie target. If the target is blank, the timeline is too short — add weeks until a figure appears.
Worked examples
A moderately active 30-year-old man going from 180 lb to 168 lb in 12 weeks
- Daily deficit
- 500 kcal/day
- Maintenance calories (TDEE)
- 2,763 kcal/day
- Daily calorie target
- 2,263 kcal/day
- Weight change per week
- 1 lb
- Check
- Within the 1–2 lb a week usually advised
A lightly active 40-year-old woman, 5 ft 4 in, going from 150 lb to 140 lb in 10 weeks
- Daily deficit
- 500 kcal/day
- Maintenance calories (TDEE)
- 1,836 kcal/day
- Daily calorie target
- 1,336 kcal/day
How big a deficit is reasonable
A loss of 1 to 2 lb (about 0.5 to 1 kg) a week is the pace most health bodies advise, which corresponds to a deficit of roughly 500 to 1,000 kcal a day. The calculator tells you whether your plan falls inside that range.
It will not show a calorie target below 1,200 kcal a day for women or 1,500 for men, the levels commonly cited as the minimum without medical supervision. Lengthen the timeline instead.
A rough rule, not a promise
The 3,500 kcal per pound figure is an approximation. As you lose weight your body burns less, so the same intake produces a shrinking deficit, and progress usually slows compared with the straight-line estimate. Recalculate every 10 lb or so.
This is an estimate for general information, not medical advice. Talk to a doctor or other qualified clinician before making health decisions based on it.
Questions people ask
What deficit do I need to lose 12 lb in 12 weeks?
500 kcal a day. Twelve pounds is 42,000 kcal, spread over 84 days. For someone with a TDEE of 2,763 kcal that means eating about 2,263 kcal a day.
Is a 1,000 calorie deficit too much?
It corresponds to about 2 lb a week, the upper end of what is usually advised, and it is only workable if your maintenance calories are high enough that intake stays above about 1,200 (women) or 1,500 (men) kcal a day.
Can I create the deficit with exercise instead?
Yes — a deficit is intake minus what you burn, so extra activity counts. Many people combine the two, for example eating 300 kcal less and burning 200 kcal more.