Pregnancy Due Date Calculator
Estimate your due date, how many weeks pregnant you are, and your current trimester.
How the due date is calculated
This calculator uses Naegele's rule, the standard method used by doctors: the estimated due date is 280 days (40 weeks) after the first day of your last menstrual period (LMP). Because that rule assumes a 28-day cycle with ovulation on day 14, the date is shifted earlier or later by the number of days your cycle differs from 28.
Pregnancy is counted from the LMP, not from conception, which is why you are already "2 weeks pregnant" at the moment of conception. Conception is estimated at about 14 days after the LMP (adjusted for your cycle length).
Trimesters
- First trimester — weeks 1 to 13
- Second trimester — weeks 14 to 27
- Third trimester — week 28 until birth
Frequently asked questions
How accurate is this?
A date-based estimate is a good starting point, but only about 4–5% of babies arrive on the exact due date; most are born within two weeks of it. An ultrasound in the first trimester is the most accurate way to date a pregnancy, and your doctor may update your due date based on it.
What if my cycles are irregular?
Enter your typical cycle length if you can. If your cycles vary a lot, the LMP method becomes less reliable and an early ultrasound is the better option.
Is this medical advice?
No. This tool is for general information only. Always follow the guidance of your doctor or midwife for your pregnancy care.