Pregnancy Due Date Calculator
Estimate your due date and pregnancy timeline from the first day of your last period.
Your Pregnancy Timeline
Key milestones
How is the due date calculated?
We use Naegele's rule: add 280 days (40 weeks) to the first day of your last period. If your cycle is longer or shorter than 28 days, we adjust accordingly.
Only about 5% of babies arrive on their exact due date; most arrive within two weeks of it. Your doctor may revise the date based on an early ultrasound.
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Due date calculator FAQ
How is my due date calculated?
Using Naegele's rule: we add 280 days (40 weeks) to the first day of your last period. If your cycle is longer or shorter than 28 days, we adjust the estimate accordingly.
How accurate is the due date?
Only about 5% of babies arrive on their exact due date; most are born within two weeks of it. Your doctor may revise the date based on an early ultrasound.
I had IVF — which calculator should I use?
For IVF pregnancies, use our IVF due date calculator, which is based on the embryo transfer date and is more precise for IVF.