Pregnancy Week Calculator
See which week and day of pregnancy you are in today, your trimester and how many days are left.
How pregnancy weeks are counted
Weeks of pregnancy are counted from the first day of your last period. “24 weeks and 3 days” means 24 full weeks and 3 days have passed since then. If you already have a due date from your care team, enter that instead and the calculator counts back 40 weeks.
The three trimesters
The first trimester runs to the end of week 13, the second from week 14 to the end of week 27, and the third from week 28 until birth. A pregnancy is called full term from 37 weeks.
Questions parents ask
Should I use my period date or my scan date?
If your care team has given you a due date from a scan, use that date. It is usually the one your appointments are planned around.
Is my information saved?
No. The calculation happens in your browser and nothing you enter is sent to us.
This tool gives general estimates for information only. It is not a diagnosis and does not replace advice from your doctor, midwife or health visitor. Read our medical disclaimer