Enter the first day of your last menstrual period to estimate your due date using Naegele's rule, plus how far along you are today and which trimester that falls in.
Estimate only — confirm with your doctor. Informational only, not medical advice.
What is a pregnancy due date calculator? A pregnancy due date calculator estimates when a baby is likely to be born and how far along the pregnancy is, based on the first day of the last menstrual period.
The standard method is Naegele's rule, which adds 280 days, or 40 weeks, to the first day of your last menstrual period. The calculator counts forward exactly 280 days from that date to estimate your due date.
Gestational age is how far along the pregnancy is, counted from the first day of your last menstrual period to today. It is shown as a number of completed weeks plus extra days, for example 12 weeks and 3 days.
The first trimester is weeks 1 through 13, the second trimester is weeks 14 through 27, and the third trimester is week 28 until birth. These ranges are counted by gestational age from the last menstrual period.
A due date from Naegele's rule is an estimate that assumes a regular 28 day cycle, and only about 4 in 100 babies are born on the exact date. An early ultrasound is more accurate. Always confirm with your doctor.