Weight Loss Calculator
Calculate how long it will take to reach your goal weight based on your daily calorie deficit. See your target date and weekly rate of loss.
Part of our Health Calculators collection.
Weight Loss Calculator
Free online calculator
Results update automatically as you type
How to Use This Calculator
- 1
Enter current and goal weight.
- 2
Select your daily calorie deficit.
- 3
See time to reach goal and target date.
How Weight Loss Timeline is Calculated
1 lb of fat ≈ 3,500 calories Weeks to Goal = (Weight to Lose × 3,500) / (Daily Deficit × 7) Safe rate: 0.5–2 lbs/week Exceeding 2 lbs/week risks muscle loss and metabolic adaptation.
Example Calculation
Example: Lose 20 lbs at 500 cal/day deficit
Inputs
currentWeight: 185goalWeight: 165weeklyDeficit: 500
Result
20 weeks (5 months)
20 lbs × 3,500 = 70,000 cal ÷ (500 × 7) = 20 weeks.
Frequently Asked Questions
Why is 2 lbs/week the maximum safe rate?
Faster loss typically means muscle loss alongside fat, which lowers your metabolism. A 500 cal/day deficit is widely considered the sweet spot — enough to lose 1 lb/week steadily without excessive hunger or muscle loss.
How do I create a 500 calorie deficit?
Combination approach works best: reduce food intake by 250–300 cal/day (eat slightly less) and increase exercise to burn 200–250 cal/day. Drastic restriction alone makes adherence difficult.
Why does weight loss slow down over time?
As you lose weight, your body burns fewer calories (smaller body = less energy needed). Recalculate your TDEE every 10–15 lbs lost and adjust intake accordingly.