Conception Calculator
Estimate a conception date by subtracting the conventional 266 days from an estimated due date.
Formula
Estimated conception = estimated due date − 266 calendar days.
Estimated due date = 2027-04-08
How to use
- Enter the estimated due date.
- Check that it is a due date, not the actual birth date.
- Read the approximate conception date.
Examples
- Due October 8, 2025: estimated conception January 15, 2025.
Frequently asked questions
Why 266 days?
It is the conventional post-ovulation duration; actual pregnancies vary.
Can this establish paternity or an exact intercourse date?
No. It cannot identify an exact conception event, intercourse date or biological parent.
Does this replace medical advice?
For information only; it does not replace a doctor or individual assessment.
Sources
Updated: