Pregnancy Due Date Calculator — Weeks, IVF & Timeline
Estimate your due date and gestational age from last period, conception, IVF transfer, ultrasound age, or a known clinical due date, with a week-by-week visual timeline.
Pregnancy date planner
Choose the best-known starting point. The result is an estimate for planning and should be confirmed with prenatal care.
Last menstrual period
42-week timeline
Due month
Pregnancy due date calculation
LMP mode starts with 280 days and adjusts for cycle length. Conception mode adds 266 days because gestational age includes about two weeks before conception.
IVF due date calculator
ACOG recommends using embryo age and transfer date for pregnancies resulting from assisted reproductive technology. This planner adds 261 days after a day-5 transfer or 263 after a day-3 transfer.
Dating by ultrasound
Enter the gestational age reported at the scan. ACOG describes first-trimester ultrasound as the most accurate method to establish or confirm gestational age.
Weeks, trimesters, and range
Gestational age is shown in completed weeks and days. ACOG defines the second trimester from 14+0 and the third from 28+0; the calendar also shows the 37–42 week range.
Frequently asked questions
How accurate is a due date calculator?
It gives an estimate. Clinical dating may use LMP, ultrasound, ART dates, and medical judgment; only about one in twenty births occurs on the exact due date according to ACOG.
What if my cycle is not 28 days?
LMP mode adds or subtracts the difference between your cycle length and 28 days.
Which IVF transfer date should I use?
Use the actual embryo transfer date and select whether the embryo was day 3 or day 5 at transfer.
Should I change my clinical due date?
No. Use the date documented by your prenatal clinician. ACOG says later changes should be reserved for rare circumstances and documented.
Sources
ACOG: Estimating the Due DateACOG: Pregnancy WeeksNHS Due Date Calculator
