Pregnancy Due Date Calculator
Calculate your pregnancy due date with this free online pregnancy calculator from your last period, conception, IVF transfer or an ultrasound scan.
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How to use Pregnancy Due Date Calculator
- 1Choose how to calculate: last menstrual period, conception date, IVF day-5 or day-3 transfer, or an ultrasound
- 2Enter the date (and your cycle length, or the weeks and days measured on the scan)
- 3Click Calculate due date to see your estimated due date, how many weeks pregnant you are, your trimester and key milestones
Frequently asked questions
How is the due date calculated?▾
The standard method (Naegele's rule) adds 280 days — 40 weeks — to the first day of your last menstrual period. If your cycle is longer or shorter than 28 days, the date is shifted by the difference.
How do I calculate my due date after IVF?▾
Following ACOG guidance, the due date is 261 days after a day-5 (blastocyst) transfer and 263 days after a day-3 transfer. Choose the matching IVF option and enter your transfer date.
How many weeks pregnant am I?▾
Pregnancy is counted from the first day of your last period, not from conception, so at conception you are already about 2 weeks pregnant. The calculator shows your gestational age today in weeks and days.
When do the trimesters start?▾
The first trimester runs to 13 weeks 6 days, the second from 14 weeks to 27 weeks 6 days, and the third from 28 weeks until birth.
What do early term, full term and late term mean?▾
ACOG defines early term as 37w0d–38w6d, full term as 39w0d–40w6d, late term as 41w0d–41w6d and post-term as 42 weeks or more.
How accurate is a due date?▾
It is an estimate: only about 4% of babies are born on their due date, and most arrive within two weeks either side. A first-trimester ultrasound is the most accurate way to date a pregnancy.
Embed Pregnancy Due Date Calculator on your website▾
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