Weight Loss Calculator Formula
Understand the math behind the weight loss calculator. Each variable explained with a worked example.
Formulas Used
Weight Loss per Week
lbs_per_week = deficit_per_day * 7 / 3500Total Weight Loss
total_loss = deficit_per_day * 7 / 3500 * weeksTotal Weight Loss (kg)
total_loss_kg = deficit_per_day * 7 / 3500 * weeks * 0.453592Weekly Deficit
weekly_deficit = deficit_per_day * 7Variables
| Variable | Description | Default |
|---|---|---|
deficit_per_day | Daily Caloric Deficit(cal) | 500 |
weeks | Time Period(weeks) | 12 |
How It Works
Weight Loss Calculation
Pounds per week = (Daily Deficit x 7) / 3,500
Approximately 3,500 calories equals one pound of body fat.
Safe Weight Loss Rates
A deficit of 500-1000 cal/day is generally considered safe.
Worked Example
A 500 calorie daily deficit over 12 weeks.
deficit_per_day = 500weeks = 12
- 01Weekly deficit = 500 x 7 = 3,500 cal
- 02Loss per week = 3,500 / 3,500 = 1.0 lb/week
- 03Total loss = 1.0 x 12 = 12.0 lbs
- 04In kg = 12.0 x 0.454 = 5.4 kg
Frequently Asked Questions
How much weight can I lose per week safely?
Most health experts recommend 1-2 lbs per week (a deficit of 500-1000 cal/day). Faster loss may lead to muscle loss and nutrient deficiencies.
Is 3,500 calories really 1 pound?
The 3,500 cal/lb rule is an approximation. Actual results vary because your metabolism adapts over time and weight loss is not purely fat.
Ready to run the numbers?
Open Weight Loss Calculator