Calculator
Pregnancy due date calculator
Count 280 days from the first day of the last menstrual period. If the cycle is not 28 days, the date moves with it. The clinician's date is the one that matters.
How the count works
ACOG's methods for estimating the due date treat 280 days from the last menstrual period as the standard for a 28 day cycle. This page uses that count, then adds or subtracts the difference when you enter another cycle length.
It does not read an ultrasound, and it does not know which period was the last real one. If you already have a due date from a visit, use that date.
ToddlerGuide is a handbook for ages 12 to 36 months. This calculator is here because the old address still gets requested. After the birth, Start here opens the toddler seasons.
Questions
How is this due date counted?
It adds 280 days to the first day of the last menstrual period. That is the count ACOG describes for a 28 day cycle. A longer or shorter cycle moves the date by the same number of days.
What if my cycle is not 28 days?
Enter the usual cycle length. The date shifts by the difference from 28. A 30 day cycle adds 2 days. A 26 day cycle subtracts 2 days.
Will my clinician use this date?
Maybe as a starting point. An exam or ultrasound can change it. The date in the chart is the one to plan around.
Source
- American College of Obstetricians and Gynecologists. Committee Opinion 700: Methods for estimating the due date. acog.org
Related: Ovulation calculator