Weight Loss Time Calculator
Plan a goal weight with a daily calorie deficit.
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Weight Loss Time Calculator by TheCalcTools
How the Weight Loss Time Calculator works
Enter your current weight, your goal and the daily calorie deficit you plan to keep.
A kilogram of body fat is roughly 7,700 kcal.
Dividing the total energy by the daily deficit gives the days needed.
The formula
Worked example
Using the default values shown in the calculator:
| Current weight (kg) | 80 |
|---|---|
| Goal weight (kg) | 72 |
| Daily calorie deficit (kcal) | 500 |
- Weight to lose = 80 − 72 = 8 kg, which is 8 × 7,700 = 61,600 kcal.
- At 500 kcal a day that takes 123 days, or 17.6 weeks.
- An average of 0.45 kg a week, 0.57% of body weight.
Result:
| Days to goal | 123 |
|---|---|
| Weeks to goal | 17.6 |
| Average loss per week (kg) | 0.45 |
| Weekly loss as % of body weight | 0.57% |
Frequently asked questions
Is the 7,700 kcal rule accurate?
It is a rough guide. Real weight change slows over time as your body weighs less and adapts, so treat the answer as an optimistic estimate.
What is a safe rate of loss?
Guidelines commonly suggest around 0.5–1 kg (1–2 lb) a week, or up to about 1% of body weight. Larger deficits should be supervised.
Sources and further reading
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This calculator gives general estimates for information and education. It is not medical advice and does not diagnose anything. Talk to a qualified health professional about your own situation. See our disclaimer.