Calorie Deficit Calculator
Turn a weight goal into a daily calorie target, choose how fast you want to lose or gain and see the deficit (or surplus) and how long it will take. Calculates in your browser.
Daily calorie target
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Show the math
A weekly weight target becomes a daily calorie adjustment:
daily adjustment = rate/week × 7,700 ÷ 7
Roughly 7,700 kcal sits in a kilogram of fat (3,500 per pound), so losing 0.5 kg a week needs about a 550-calorie daily deficit. Keep deficits moderate, around 0.5–1% of body weight per week, to protect muscle and stay consistent. Targets below about 1,200 kcal a day for women or 1,500 for men are flagged (below 1,500 if you don't pick a sex), and anything under 800 kcal is a very-low-calorie diet that needs a doctor's supervision.
What this does
A calorie deficit calculator turns a weight goal into a daily calorie target, you choose how fast to lose or gain and it shows the deficit (or surplus) and how long it will take.
How it works
Roughly 7,700 kcal is stored in a kilogram of body fat (about 3,500 per pound). The tool spreads your weekly target over seven days to find the daily calorie adjustment from your maintenance level.
How to use it
- Enter your maintenance calories (TDEE) and, optionally, your sex for the minimum-intake check.
- Choose lose or gain, and a rate per week.
- Add your current and goal weight to see how long it will take.
- Read the daily calorie target, deficit or surplus, and any warnings.
Understanding your result
A common pace is about 0.5–1% of body weight per week; 0.5 kg (about 1 lb) a week is roughly a 500–550 kcal daily deficit. Larger deficits risk muscle loss and are hard to sustain; re-check maintenance every few weeks as metabolism adapts. Targets under about 1,200 kcal a day for women or 1,500 for men (1,500 if you leave sex blank) are flagged.
Example
Losing 0.5 kg a week needs about a 550 kcal daily deficit, for a 2,200 kcal maintenance, that is around 1,650 kcal a day.
Sources & methodology
- NIH, Body Weight Planner, How calorie change drives weight change
- USDA, Dietary Guidelines for Americans, Healthy calorie targets
- Harvard Health Publishing, Calorie counting made easy, Minimum intake without medical supervision: 1,200 kcal (women), 1,500 kcal (men)
- NIDDK, Very low-calorie diet (definition), About 800 kcal a day or less, under medical supervision
- Helms, Aragon & Fitschen (2014), J Int Soc Sports Nutr, Losses of about 0.5–1% of body weight a week maximize muscle retention
Last updated .
Frequently asked questions
How low is too low?
Most guidance advises at least about 1,200 kcal a day for women and 1,500 for men without medical supervision, and anything under 800 kcal is a very-low-calorie diet that needs a doctor. The calculator warns when a target falls below these levels (it uses the 1,500 kcal floor if you don’t choose a sex) or when the rate is faster than about 1% of your body weight a week.
How big a deficit is safe?
A common guideline is about 0.5–1% of body weight per week, often around 0.5 kg (about 1 lb). That maps to roughly a 500–550 kcal daily deficit. Larger deficits risk muscle loss and are hard to sustain.
Where does the 7,700 figure come from?
Roughly 7,700 kcal is stored in a kilogram of body fat (about 3,500 per pound). The tool spreads your weekly target over seven days to find the daily calorie adjustment.
Why is the estimate not exact?
Metabolism adapts as you lose weight and the 7,700 figure is an average, so real results vary. Re-check your maintenance calories every few weeks and adjust.
Do you keep my numbers?
No. Everything is calculated locally in your browser.
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