Pregnancy Due Date Calculator
Find your estimated due date and track your pregnancy week by week.
What is it?
A pregnancy due date calculator estimates the date your baby is most likely to be born, based on either the first day of your last menstrual period (LMP) or your known conception date. The result is called the Estimated Due Date (EDD) or Expected Date of Delivery (EDD). Most pregnancies last approximately 40 weeks (280 days) from the first day of the last period, or about 38 weeks from conception. This is the same standard used by midwives and obstetricians worldwide, based on Naegele's Rule — a formula developed in the 19th century and still considered accurate as a starting point for prenatal care planning. Beyond the due date itself, this tool also shows your current pregnancy week and day, the trimester you are in, how many days remain until your due date, and important milestone dates such as the typical timing for the anatomy scan (around week 20) and the transition between trimesters. All calculations are performed instantly in your browser — your personal information is never stored or shared.
How to use it
- Choose your calculation method: "Last menstrual period" (most common) or "Conception date".
- Enter the relevant date using the date picker.
- For LMP calculations, you can adjust the average cycle length if yours differs from the standard 28 days.
- Your estimated due date appears immediately, along with your current pregnancy week and trimester.
- Scroll down to see key milestone dates and a trimester overview.
Why use this tool
Knowing your estimated due date is one of the first things expectant parents want to find out. This free calculator gives you an immediate, accurate estimate without needing to call a clinic or wait for an appointment. It uses the same Naegele's Rule formula used in medical practice. The tool goes beyond just the date — it tells you exactly which week and trimester you are in right now, how many days are left until your due date, and when major prenatal milestones typically occur. This helps you plan appointments, share the news with family, and mentally prepare for each stage of pregnancy. Everything runs in your browser. No account, no email, no personal data stored. The calculator is suitable for all screen sizes, including mobile, so you can check it any time, anywhere. Remember: the estimated due date is a statistical average. Only about 5% of babies are born exactly on their due date, and a normal birth can occur anywhere between 37 and 42 weeks. Always confirm your due date with your healthcare provider through an ultrasound dating scan.
Frequently asked questions
How accurate is the estimated due date?
The EDD calculated using Naegele's Rule is a statistical estimate based on a 28-day cycle. A first-trimester ultrasound is the most accurate dating method and may adjust this date. Only about 5% of babies arrive on their exact due date — most are born within two weeks before or after.
What if my cycle is not 28 days?
This calculator lets you adjust your average cycle length. If your cycle is longer than 28 days, ovulation (and therefore conception) likely occurs later, shifting your due date forward. If it is shorter, the due date shifts earlier.
When does each trimester start?
The first trimester runs from week 1 to the end of week 12. The second trimester covers weeks 13 through 26. The third trimester begins at week 27 and runs to birth (typically around week 40).
Can I use this after a positive pregnancy test?
Yes. If you know the date of your last period, enter it now. If you only know your conception date from IVF or a known ovulation date, use the conception-date option instead.
What is Naegele's Rule?
Naegele's Rule calculates the due date by adding 280 days (40 weeks) to the first day of the last menstrual period. It assumes a regular 28-day cycle with ovulation on day 14. It has been the standard method in obstetrics since the 19th century.