Calculator

Pregnancy Due Date Calculator

Due date, current week and trimester from the last period, conception, ultrasound or IVF.

Calculate from

Date

Usual cycle length

days

Age on the scan

weeks

and

days

Embryo age

3-day 5-day

Results update as you type.

Estimated due date

–

Trimester: –
Estimated conception: –
End of first trimester: –
End of second trimester: –
Full term from: –
Days to go: –

How the due date is estimated

Pregnancy is counted from the first day of the last menstrual period (LMP), about two weeks before conception. The due date is LMP + 280 days (40 weeks), adjusted for cycles longer or shorter than 28 days. From a known conception date it is + 266 days; for an IVF transfer, + 266 days minus the embryo’s age.

Only about 1 in 25 babies arrives on the due date itself; most are born between 37 and 42 weeks. An early ultrasound is the most accurate way to date a pregnancy, so follow your doctor’s dating if it differs.