Calculator
Due Date Calculator
Estimate your due date and how far along you are from your last period, conception date, IUI date or IVF embryo transfer date.
Due Date Calculator
Pick how you want to calculate, enter a date and see your estimated due date and gestational age. IUI and IVF dates are supported.
Your estimate
- Estimated due date
- Gestational age today
- End of first trimester
- Second trimester starts
Only about 4% of babies arrive on their estimated due date, and a normal pregnancy can deliver from 37 to 42 weeks. Your clinician may adjust the date after an early ultrasound.
About this tool
A full-term pregnancy is counted as 40 weeks from the first day of the last menstrual period, which is about 38 weeks from conception. If your cycle is longer or shorter than 28 days, the due date is adjusted by the difference.
For IUI, the calculator treats the procedure day as the conception date. For IVF, it counts back from the embryo’s age at transfer: a day-5 transfer is 261 days before the due date and a day-3 transfer is 263 days before.
Your clinician may revise the date after an early ultrasound, especially when cycles are irregular. Treat the result as a guide, not a deadline.
What to keep in mind
- Only a small share of babies arrive on their due date. Delivery between 37 and 42 weeks is considered full term in most guidance.
References
We rely on government health agencies, professional medical organizations, peer-reviewed research and academic institutions. Read our sourcing standards.