Weight Loss Timeline Calculator
Enter your current weight, goal weight and daily calorie deficit to see how many weeks it takes to reach your goal — with a week-by-week weight chart.
How to use this tool
- Enter current weight, goal weight and daily calorie deficit in the fields above.
- Results update instantly as you type — or click Calculate.
- Read your weeks to goal and the full breakdown beneath it.
One pound of fat equals roughly 3,500 calories. A sustained daily deficit drives predictable weight loss at about 1 lb per week per 500 kcal/day deficit.
Not medical advice. Consult a healthcare professional before starting any weight-loss programme, especially deficits above 750 kcal/day.
⚠ This tool is for general information and education only and is not medical advice. Consult a qualified healthcare professional before making health decisions.
Formula
Weekly weight loss: lbs/week = Daily Deficit (kcal) × 7 / 3,500
Weeks to goal: Weeks = ⌈(Current Weight − Goal Weight) / (lbs/week)⌉
Months to goal: Months = Weeks / 4.33
How it works
The calculator uses the widely cited energy-balance rule that one pound of body fat stores approximately 3,500 kcal. A sustained daily calorie deficit is multiplied by seven to give a weekly calorie deficit, then divided by 3,500 to estimate pounds lost per week. The total pounds to lose divided by this weekly rate gives the number of weeks required.
This linear model is a planning estimate. In practice, metabolic adaptation, water retention, and adherence variation mean real progress is rarely perfectly linear. The 3,500 kcal/lb figure is an approximation and individual results will vary.
Worked example
- Current weight: 200 lb. Goal weight: 170 lb. Daily calorie deficit: 500 kcal/day.
- Weekly loss = 500 × 7 / 3,500 = 3,500 / 3,500 = 1.0 lb/week.
- Pounds to lose = 200 − 170 = 30 lb. Weeks = ⌈30 / 1.0⌉ = 30 weeks.
Weeks to goal: 30. Weight loss rate: 1.00 lb/week.
Common mistakes to avoid
- Treating the 3,500-calorie-per-pound rule as exact — actual weight loss slows as body weight and TDEE fall, so the linear timeline becomes optimistic after the first few weeks.
- Entering a daily deficit above 1,000 kcal without recognizing that very large deficits cause muscle loss and metabolic adaptation, undermining the projection.
- Using the chart as a fixed schedule — caloric needs change as weight drops, requiring recalculation every 10-15 lbs lost.
Key terms
- Calorie deficit
- The state of consuming fewer calories than the body burns, causing it to draw on stored energy (primarily fat) to make up the shortfall.
- 3,500 kcal per pound rule
- An approximation stating that one pound of body fat is equivalent to roughly 3,500 kcal; often used to estimate weight-loss rates from a sustained calorie deficit.
- TDEE (Total Daily Energy Expenditure)
- The total calories burned in a day, including basal metabolism, physical activity, and the thermic effect of food.
- Metabolic adaptation
- The reduction in metabolic rate that can occur during a calorie deficit as the body attempts to conserve energy.
- Sustainable deficit
- A calorie deficit modest enough to be maintained long-term without triggering severe hunger or muscle loss; commonly cited as 500 kcal/day.
Frequently asked questions
- Why 3,500 calories per pound?
- The 3,500 kcal/lb rule is a widely used approximation. Actual results vary with age, sex, body composition and metabolic adaptation.
- Is 500 kcal/day a safe deficit?
- A 500 kcal/day deficit targets ~1 lb/week loss and is generally considered safe for most adults, but consult your doctor if you have health conditions.