Calculate from the last menstrual period, conception date, IVF transfer, or a known estimated due date.
Your estimate
Estimated due date
Enter dating information.
Pregnancy milestone schedule
| Milestone | Estimated date |
|---|
How pregnancy dating works
Pregnancy is conventionally dated from the first day of the last menstrual period. With a 28-day cycle, the estimated due date is 280 days later. This calculator adjusts that estimate when a cycle length from 21 to 35 days is entered.
For a conception date, the estimate adds 266 days. IVF estimates account for embryo age by adding 263 days after a day-3 transfer or 261 days after a day-5 transfer.
Understanding the timeline
Gestational age starts approximately two weeks before conception in a typical cycle. This tool marks 12 weeks, 20 weeks, the start of the third trimester at 28 weeks, early term at 37 weeks, and the estimated due date at 40 weeks. Appointments and testing schedules should always follow your maternity-care team.
Frequently asked questions
Is the estimated due date exact?
No. It is a clinical estimate, and only a small proportion of births occur on the exact date.
Why might ultrasound give another date?
Last-period recall, irregular cycles, and variation in ovulation can affect menstrual dating. An early accurate ultrasound may provide better information.
Which date should IVF pregnancies use?
Use the embryo transfer date and the embryo age provided by the fertility clinic, then confirm the official due date with the treating clinician.
Medical information notice
This calculator does not confirm pregnancy, fetal health, or a clinical due date. Contact a qualified maternity-care professional for pregnancy dating and care. Seek urgent medical help for heavy bleeding, severe abdominal pain, fainting, breathing difficulty, or other concerning symptoms.
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