See your estimated due date, pregnancy week on any date, and estimated conception timing. When you enter more than one pregnancy date, the result also compares them.
Load it only if this is your information. Anyone using this browser profile may be able to see saved pregnancy dates.
Your pregnancy timeline
| Based on | Due date | Difference | Use |
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| Milestone | Date |
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For a 28-day cycle, the calculator adds 280 days to the first day of the last period and adjusts for cycle length. It adds 266 days to known ovulation or fertilization. Embryo-transfer dating subtracts the embryo’s age before applying the 266-day convention. An ultrasound report is converted from its stated due date or gestational age.
The calculator shows one conventional estimate of conception timing. It is most specific when fertilization is known. When the estimate comes from a last period, ultrasound report, or established due date, actual ovulation and conception may have occurred earlier or later.
A result of 24 weeks and 3 days means 24 full weeks have been completed and week 25 is in progress. Choose today or another date to see when that pregnancy week begins and ends.
Pregnancy is dated from the first day of the last menstrual period, approximately two weeks before fertilization. The calculator puts every entered date on that same timeline.
First-trimester crown-rump length is the most accurate routine ultrasound dating method, while last-period estimates depend on the date being reliable and cycles being reasonably regular. Even after preterm births and pregnancies with related medical conditions were excluded, ovulation-based gestation still spanned 37 days in Jukic et al.