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Calorie Deficit Calculator

Calculate your daily calorie deficit and estimated weeks to reach a weight-loss goal.

Introduction

Calorie Deficit Calculator — Calculate your daily calorie deficit and estimated weeks to reach a weight-loss goal. Enter TDEE (kcal/day), Target calories/day, Goal weight loss (lb) to get an instant, accurate result.

Formula

Daily deficit = TDEE − target calories. Weeks to goal = (goal loss in lb × 3500) / (weekly deficit), using the standard approximation that 3,500 kcal ≈ 1 lb of body fat.

Step-by-step

  1. Enter the TDEE (kcal/day).
  2. Enter the Target calories/day.
  3. Enter the Goal weight loss (lb).
  4. Click Calculate to see your result instantly.

Real-world example

Example: With TDEE (kcal/day) = 2500, Target calories/day = 2000, Goal weight loss (lb) = 10, the Calorie Deficit Calculator gives Daily Deficit: 500, Weekly Deficit: 3500, Weeks To Goal: 10.

Frequently Asked Questions

Where does the 3,500-calorie figure come from?
It's a long-standing approximation (Wishnofsky, 1958) for the calories in a pound of body fat. Real-world weight loss varies by individual and slows over time.
Is a bigger deficit always better?
No — very large deficits risk muscle loss, fatigue, and are hard to sustain. A moderate deficit of 500 kcal/day is a common, more sustainable target.
What inputs does the Calorie Deficit Calculator need?
You'll need to provide: TDEE (kcal/day), Target calories/day, Goal weight loss (lb). All fields use sensible defaults, so you can see a working example immediately and then adjust the values to match your own numbers.
How accurate is the Calorie Deficit Calculator?
The Calorie Deficit Calculator applies the formula exactly as calculated — Daily deficit = TDEE − target calories. Weeks to goal = (goal loss in lb × 3500) / (weekly deficit), using the standard approximation that 3,500 kcal ≈ 1 lb of body fat. — so results are precise for the inputs you provide. Accuracy depends on entering correct, realistic input values.
Is this a medical diagnosis?
No. The Calorie Deficit Calculator provides an estimate based on standard formulas and general population data, not a medical diagnosis or personalized clinical advice. Individual results can vary — consult a doctor or other qualified healthcare provider for medical concerns.
Is the Calorie Deficit Calculator free to use?
Yes, the Calorie Deficit Calculator is completely free, requires no signup, and runs instantly in your browser.

About the Calorie Deficit Calculator

The Calorie Deficit Calculator uses a real, verifiable formula — Daily deficit = TDEE − target calories. Weeks to goal = (goal loss in lb × 3500) / (weekly deficit), using the standard approximation that 3,500 kcal ≈ 1 lb of body fat. — so results are accurate every time, not an approximation.