Pregnancy Due Date Calculator
Find your pregnancy due date (EDD) from the first day of your last period (LMP).
These are example values. Enter your own.
Result
Turn on JavaScript to see live results. Below is an example calculation.
This is an estimate. Your doctor will confirm dates with a scan.
How it's calculated
Doctors use Naegele’s rule: your estimated due date (EDD) is 280 days, or 40 weeks, after the first day of your last menstrual period (LMP). This assumes a 28-day cycle. If your cycle is longer or shorter, the due date moves later or earlier by the same number of days. Formula: due date = LMP + 280 days + (cycle length − 28). Example: if your last period started on 1 January 2026 and your cycle is 28 days, your due date is 8 October 2026. Pregnancy weeks are counted from your LMP, about two weeks before conception. This is called gestational age, and it is how doctors and ultrasound reports count weeks. A pregnancy has three trimesters: the first trimester is weeks 1 to 13 (months 1 to 3), the second is weeks 14 to 27 (months 4 to 6), and the third is weeks 28 to 40 (months 7 to 9). Only about 4% of babies are born on their exact due date. Most arrive in the two weeks before or after it. An early ultrasound scan is more accurate than the LMP method, especially if your cycles are irregular.
Frequently asked questions
How is the Pregnancy Due Date calculated?
Add 280 days (40 weeks) to the first day of your last period. If your cycle is not 28 days, add or subtract the difference. The calculator does this for you.
What is EDD in pregnancy?
EDD means estimated date of delivery, which is your due date. It is usually 40 weeks after the first day of your last period.
What is LMP?
LMP is the first day of your last menstrual period. It is the starting point for counting pregnancy weeks and your due date.
How many weeks pregnant am I?
Count the weeks from the first day of your last period to today. For example, if your last period started 10 weeks ago, you are 10 weeks pregnant.
How accurate is a due date calculator?
It gives a good estimate for women with regular cycles. Only about 4% of babies are born on the exact date. An ultrasound in the first trimester is more accurate.
Can I use this calculator after IVF?
IVF due dates are usually worked out from the embryo transfer date, not the last period. Ask your fertility clinic for your exact date. Results are estimates for information only, not medical advice.
Is this calculator free and private?
Yes. It is free to use and needs no sign-up. All calculations run in your browser, so the numbers you enter are not sent to our server.
Results are estimates for information only, not professional advice. · Last updated:
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