Pregnancy Due Date Calculator
About the Pregnancy Due Date Calculator
Estimate your due date and track pregnancy milestones week by week from the first day of your last menstrual period (LMP). The calendar view shows trimester boundaries and key checkpoints along the 40-week journey. All calculations happen locally in your browser — no dates or personal information are transmitted or stored on any server.
This tool works in your browser: the files and text you use are processed on your device and are not uploaded.
How to use it
- Open the Pregnancy EDD tab.
- Enter the first day of your last menstrual period.
- Read your estimated due date and the current week of pregnancy.
Frequently asked questions
How is the due date calculated?
Using Naegele’s rule: 280 days (40 weeks) from the first day of your last menstrual period. This assumes a 28-day cycle with ovulation on day 14; an ultrasound in early pregnancy can refine the estimate.
How accurate is a due date?
Only about 4–5% of babies arrive on their exact due date. Most are born within two weeks either side — full term is anywhere from 37 to 42 weeks. Treat the date as the centre of a window, not a deadline.
What if my cycles are irregular or longer than 28 days?
The LMP method becomes less reliable with irregular cycles. A first-trimester dating ultrasound (ideally between 8 and 13 weeks) is the most accurate way to date the pregnancy in that case.
What are the trimesters?
First trimester: weeks 1–13 (organ formation). Second: weeks 14–27 (growth; often the most comfortable). Third: weeks 28–40+ (rapid weight gain and preparation for birth). Antenatal checkups become more frequent as you progress.
This tool provides general estimates for informational purposes only and is not medical advice. Always consult a qualified healthcare professional about your health, diet, or pregnancy.