Due Date Calculator
How is my due date calculated?
First day of your last period
The most common way to calculate your due date is by counting 40 weeks from the first day of your last menstrual period (LMP). And that’s how most healthcare providers do it.
This method is based on the idea that women typically ovulate about 2 weeks after their period starts and pregnancy typically lasts about 38 weeks. Plus it’s usually easier to remember when your period started than to figure out what day you conceived.