CALCULATOR · FREE免费 · Free
Conception Date Calculator
Enter a due date to estimate conception about 266 days earlier. Natural conception cannot be pinned to a single day, so this is an estimate.
--Conception year · year
--Conception month · month
--Conception day · day
--Conception date · date
Estimates only; verify on site before ordering or building.
Example
| Item | Value | Unit |
|---|---|---|
| Due year | 2026 | year |
| Due month | 10 | month |
| Due day | 8 | day |
| Conception year | 2026 | year |
| Conception month | 1 | month |
| Conception day | 15 | day |
| Conception date | 2026-01-15 | date |
Where people go wrong
- Treating the due date as the conception date, which is about nine months off.
- Counting back 280 days instead of 266.
- Ignoring that sperm can survive for days, so conception may not happen on the same day.
FAQ
Can the conception date be known exactly?
Natural conception is hard to pin to a single day; you get a window. Fertility treatment can be more precise.
Why 266 days?
Conception to due date is about 266 days; from the last period it is 280 days, roughly two weeks more.