Compare calculators
Both calculators run independently β change the inputs on either side to compare results.
Pregnancy
Conception Date Calculator
Estimates the most likely conception date by counting back 266 days (38 weeks) from your due date. Useful when you know your due date but want to narrow down when fertilization likely occurred.
Fill in the required fields to see your result.
Pregnancy
Due Date Calculator
Estimates how many days remain until your due date and your current pregnancy week from how many days ago your last period (or conception/ultrasound reference) was, plus cycle length and any ultrasound adjustment.
Fill in the required fields to see your result.
Key differences
| Conception Date Calculator | Due Date Calculator | |
|---|---|---|
| Category | Pregnancy | Pregnancy |
| Inputs required | 1 | 4 |
| Result | Days since conception (days ago) | Due Date Countdown |
| What it does | Estimates the most likely conception date by counting back 266 days (38 weeks) from your due date. Useful when you know your due date but want to narrow down when fertilization likely occurred. | Estimates how many days remain until your due date and your current pregnancy week from how many days ago your last period (or conception/ultrasound reference) was, plus cycle length and any ultrasound adjustment. |