Weight Loss Timeline Calculator
Enter your current weight, goal weight, and daily calorie deficit to estimate how many weeks it will take to reach your goal, based on the commonly cited approximation that roughly 3,500 calories equals one pound of body weight.
How the Weight Loss Timeline formula works
A widely used (though approximate) estimate:
Weeks to goal = (Weight to lose (lb) × 3,500) / (Daily deficit × 7)
Step-by-step calculation
- Subtract your goal weight from your current weight to find total pounds to lose.
- Multiply by 3,500 (the commonly cited calorie equivalent of one pound of body fat).
- Divide by your daily calorie deficit multiplied by 7 to get weeks to goal.
Worked example
20 pounds to lose at a 500-calorie daily deficit: Weeks = (20 × 3,500) / (500 × 7) = 70,000 / 3,500 = 20 weeks, or about 5 months.
Frequently asked questions
Is the 3,500-calorie-per-pound rule exactly accurate?
It's a widely used approximation, not an exact figure — actual weight loss varies by individual due to metabolic adaptation, water weight fluctuations, and body composition changes, so real-world results often deviate from this simple linear estimate, especially over longer timeframes.
What's a safe daily calorie deficit?
A deficit of 500-750 calories/day is commonly cited as producing a moderate, generally sustainable rate of loss (roughly 1-1.5 lb/week) for many adults — very large deficits are often harder to sustain and can carry other risks, so consulting a healthcare provider is worthwhile before pursuing an aggressive deficit.