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Choose the dating information you have and the page will calculate a planning estimate plus a gestational-age timeline. Keep the clinical estimated due date from your prenatal record as the source of truth for appointments, testing and care decisions.
This visual spans 37 weeks through 42 weeks as a planning reference; it is not a prediction of when labor will begin. ACOG labels 37 0/7–38 6/7 early term, 39 0/7–40 6/7 full term, 41 0/7–41 6/7 late term, and 42 0/7 onward postterm.
Bump to Baby is a printable keepsake journal that covers pregnancy and the first year — appointments, milestones, and firsts, in one place.
The calculator applies common calendar formulas to the dates you enter. Clinical pregnancy dating uses a hierarchy of information rather than treating every input method as interchangeable, and the estimated due date used for care should be documented by the prenatal team.
Due date = first day of your last period + 280 days, adjusted for your cycle length if it's not the textbook 28 days. It's the fastest estimate to get, but it assumes ovulation happened on day 14, which isn't true for everyone.
This page uses conception date + 266 days as a planning estimate when you enter a conception or ovulation date. The clinical estimate may differ depending on the dating information available.
For pregnancies from assisted reproductive technology, clinical dating uses the embryo age and transfer date. This page applies the corresponding calendar arithmetic for a planning estimate; use the ART-derived date documented by the care team for clinical decisions.
First-trimester ultrasound is the most accurate ultrasound method for establishing or confirming gestational age. Later scans have wider dating uncertainty, so a date entered here should not be used to re-date a pregnancy on your own.
An estimated due date is not a promise of a birth date. The timeline below is a planning reference only; clinical term categories and decisions about monitoring or delivery belong with the prenatal care team.
Most due dates are estimated using Naegele's rule: the first day of your last menstrual period plus 280 days (40 weeks), assuming a textbook 28-day cycle. Conception date, IVF transfer date, and ultrasound scans give more personalized estimates.
It's an estimate, not a guarantee — only about 1 in 20 babies arrive on their exact due date. Full term is generally considered anywhere from 3 weeks before to 2 weeks after the estimated date. A healthcare provider may adjust the date based on an ultrasound or your specific cycle length.