Pregnancy Due Date Calculator

Estimate your baby’s due date from your last menstrual period, conception date or IVF transfer date, and see how many weeks pregnant you are.

What is the Pregnancy Due Date Calculator?

The estimated due date (EDD) is 40 weeks from the first day of the last menstrual period, assuming a 28-day cycle.

How does it work?

Naegele’s rule adds 280 days to the LMP, adjusted for longer or shorter cycles. Conception adds 266 days; IVF transfers add 263 (day 3) or 261 (day 5) days.

Formula

EDD = LMP + 280 days + (cycle length − 28)

Example

An LMP of 1 January 2026 with a 28-day cycle gives a due date of 8 October 2026.

Frequently asked questions

Will my doctor’s date differ?

Often slightly. An early ultrasound can refine the due date, and your doctor’s date should be used for care decisions.

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