Health
Pregnancy Due Date Calculator
Estimate your due date and gestational age from your LMP, ultrasound, ovulation, assisted reproduction, or a date provided by your healthcare professional.
Main calculation
When might your baby be born?
Choose the information you have available. If your clinician has already given you an official due date, use it as the primary reference.
Term window and important dates
The following dates are calculated from the reference due date. Use them as a guide when speaking with your healthcare team.
Term window
Complete the calculator to see the ranges.
Important dates
Complete the calculator to see the dates.
How to interpret the result
The estimated due date is a reference date, not an exact appointment. That is why we also show a term window and a confidence level based on the method used.
Which information should you use?
If you have an official due date, use it first. Otherwise, an early ultrasound or assisted-reproduction records are generally more precise than an approximate date of intercourse.
Frequently asked questions
How is an estimated due date calculated?
The most common method adds 280 days to the first day of your last menstrual period. It can also be estimated from ovulation, ultrasound, assisted reproduction, or an official due date provided by your healthcare team.
Is the LMP the first or last day of the menstrual period?
This calculation uses the first day of bleeding from your last menstrual period. Using another day can shift the estimated due date.
How accurate is an estimated due date?
It is an estimate. Only a small percentage of babies are born on that exact day. The calculator displays a confidence level based on the information used.
What if the ultrasound and LMP produce different dates?
Small differences are common. If the dates differ by several days, your physician or midwife can determine which one to use as the official due date.
How is the due date calculated for IVF?
If you know the embryo transfer date, add 266 days minus the embryo's age. For example, for a day-5 transfer, add 261 days to the transfer date.
What if my estimated due date has passed?
A baby may not be born exactly on the estimated due date. Stay in contact with your healthcare team, especially if several days have passed.