Pregnancy Due Date Calculator — Weeks & EDD
Estimate pregnancy week and due date from your last period or conception date, with cycle-length adjustment and a week-by-week timeline.
The date your last period started
Usually 28 days (range 21–35)
This is an informational estimate. Irregular cycles, IVF and ultrasound dating require clinical assessment. Follow the gestational age and due date recorded by your qualified maternity-care professional.
Want to plan a pregnancy and find your ovulation day?Ovulation Calculator →How to use the calculator
Three simple steps to find your pregnancy week, due date and what is happening this week.
Pick a mode
By the first day of your last period, or by conception date if you know it precisely.
Enter the date
Provide the date and (for LMP mode) your cycle length so the ovulation correction is accurate.
Get the result
You will see the current week, due date, trimester and milestones for your stage of pregnancy.
Calculator features
Two calculation modes
By last menstrual period (LMP) with cycle-length adjustment, or directly by known conception date.
Weekly milestones
Short, general development pointers for key weeks without replacing your individual antenatal-care plan.
Private, instant estimate
Dates are calculated in your browser without registration; no country-specific leave rule is presented as universal.
Frequently asked questions about pregnancy weeks
How is gestational age calculated?
Doctors use the gestational age, counted from the first day of the last menstrual period (LMP), not from conception. This is convenient because most women remember their period date, but few know the exact conception date. Gestational age is about 2 weeks more than the actual embryo age, because ovulation and conception typically happen in the middle of the cycle.
What is the EDD and how is it computed?
EDD stands for Estimated Due Date. By Naegele's rule: EDD = first day of last period + 280 days (40 gestational weeks). If your cycle is longer or shorter than 28 days, the calculator shifts the EDD accordingly — for a 32-day cycle, the EDD moves 4 days later. In conception mode, EDD = conception date + 266 days (38 weeks).
Why can my estimated due date change?
Last-period dating assumes a regular cycle and ovulation around the middle of it. Irregular cycles, uncertain dates, assisted reproduction and an early ultrasound can change the clinical estimate. Use the due date documented by your maternity-care professional.
How accurate is the calculator?
A last-period calculation is approximate because the exact ovulation date varies. First-trimester ultrasound is the most accurate method to establish or confirm gestational age. This calculator is informational and does not replace professional maternity care.
Sources and limitations
The due-date method and limitations are checked against clinical guidance; your clinician's documented obstetric estimate takes priority.