How to use this calculator
Compare the arithmetic effect of a selected calorie deficit on an adult maintenance estimate and target weight. Read the timeline as a simplified scenario.
How the estimate is calculated
Maintenance is estimated from resting energy and an activity factor. The tool divides the selected weekly calorie deficit by 7,700 kcal/kg to calculate an illustrative weekly change, then projects that same change across successive weeks.
Daily scenario calories equal estimated maintenance minus the selected deficit. The implementation bounds its projection to 520 weeks and rejects invalid or nonpositive results.
What the estimate cannot tell you
The 7,700 kcal/kg conversion and constant weekly change do not model metabolic adaptation, changes in expenditure, water weight or individual outcomes. A positive calorie number alone does not establish a safe intake. The NIDDK Body Weight Planner provides a more detailed model; medical or dietary advice should be individualized.
Worked example
A 500 kcal/day scenario gives 3,500 kcal/week. Dividing by 7,700 gives about 0.455 kg/week in this simplified model, not a promised real-world loss.