Calculation of the best estimated due date (EDD) is based on the day of the date of ovulation and fertilization. The EDD can then be calculated by adding 266 days to the day of ovulation/fertilization.
If you don't know the exact date of ovulation, then your due date can be calculated by adding 40 weeks (280 days) to the approximate first day of your last menstrual period in a 28-day cycle. If your cycles are longer or shorter than 28 days, then the day of ovulation may change and this calculator takes that into condideration when calculating the EDD.
Find out why estimating the correct pregnancy due date is important. Occasionally, it may be necessary to recalculate the estimated due date EDD based on other information such as on an ultrasound that was done and showed different information than a due date based only on your last period.
Try our Reverse Due Date Calculator to find out when you became pregnant. There, you can enter your due date and we will calculate the exact days of conception. More importantly, we will provide the range of dates that you may have made love and got pregnant.
Please also look at the Interactive Pregnancy Wheel.
How To Use the Pregnancy Due Date Calculator
The first step is to know the first day of your last menstrual period and the length of your menstrual cycle. Enter the date of the first day of the last menstrual period and the cycle length. Alternatively, you can also enter the day of ovulation, the weeks and days of the pregnancy on ultrasound, or the IVF egg or embryo transfer date.
The pregnancy due date calculator wil then calculate the exact date the baby will be due as well as other important events such as the date of implantation, when the baby will start moving and dates for important tests like amniocentesis, ultrasound, or glucose screen.
In addition to the Pregnancy Due Date Calculator, there is also a unique and handy offline tool called the Ovulation Calendar & 9-Month Pregnancy Wheel that helps determine a woman's ovulation date and serves as a traditional pregnancy wheel after conception has occurred.
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