How this calculator works
A calorie deficit is the gap between energy expenditure and intake. The common 7,700 kcal-per-kilogram conversion is convenient arithmetic, but the body is not a static bank account.
As weight changes, energy expenditure and spontaneous movement can change too. Water, glycogen, digestion and the menstrual cycle also move scale weight independently of body fat.
Daily deficit = estimated TDEE − planned intake. The tool uses 7,700 kcal per kilogram only to create a simple initial projection; real weight change is dynamic.
How to use the result
Use the timeline to compare plans, not to set a guaranteed finish date. A weekly average can stall for one or two weeks while fat loss continues underneath water fluctuations.
If the projection exceeds roughly 1% of body weight per week, the plan is aggressive for many people. Hunger, training quality, recovery and nutrient adequacy deserve as much attention as speed.
Get a more reliable result
Use a maintenance estimate calibrated with at least two weeks of average intake and body-weight data whenever possible. Enter the intake you can sustain, not the lowest number you could tolerate briefly. Check the projected weekly percentage against training performance, hunger, recovery and medical context.
Common errors that change the answer
- Using 7,700 kcal per kilogram as a guaranteed deadline rather than a rough model.
- Reducing intake after a few flat scale days that are easily explained by water.
- Pursuing the largest possible deficit despite poor sleep, low energy or declining training.
What to do next
- Start with the smallest deficit likely to produce a measurable trend.
- Keep protein and resistance training in place to support lean mass.
- Pause and get help if the plan brings persistent fatigue, dizziness, missed periods or obsessive food thoughts.
Guides that support this calculator
Frequently asked questions
Is 7,700 kcal exactly one kilogram of fat?
No. It is a rough planning conversion. Actual tissue loss and metabolic adaptation make real change non-linear.
Why did weight rise during a deficit?
Short-term water, sodium, carbohydrate, training inflammation and gut contents can outweigh fat change on the scale.
How often should I adjust calories?
Usually not from a few days. Review two to four weeks of consistent data unless symptoms or safety concerns require earlier action.