Pregnancy Calculator

How the calculation works

Enter the first day of your last period and your usual cycle length. The due date is 280 days after the start of the last period, adjusted if your cycle is not 28 days. The timeline shows the date at every fourth week.

Formula used

Due date = first day of last period + 280 days + (cycle length − 28)

Example

A last period starting on 1 August 2026 with a 28-day cycle gives a due date of 8 May 2027.