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Pregnancy Conception Calculator

Work backwards from your due date to estimate when conception happened.

How it works Report a problem

Conception Calc

Reverse Conception Date Estimation

About the Pregnancy Conception Calculator

Work backwards from your due date to estimate when conception happened.

How to use the Pregnancy Conception Calculator

  1. Enter your Known Due Date.
  2. Press Estimate Conception.

Formula and method

Conception is estimated at about 266 days (38 weeks) before the due date.

Tips

  • Only around 5% of babies arrive on the exact due date.

Frequently asked questions

Why is the conception date a range?
Sperm can survive for several days, and ovulation timing varies.