Pregnancy Calculator

See how many weeks pregnant you are, your trimester and your due date.

How it works

The calculator works out your due date from the date you enter, then counts the days from the start of your pregnancy to today. Weeks are counted from the first day of your last period, as doctors do, so week 1 begins about two weeks before conception.

The three trimesters

• First trimester: weeks 1 to 13
• Second trimester: weeks 14 to 27
• Third trimester: week 28 until birth, with a due date at 40 weeks

Worked example

If the first day of your last period was January 10, 2027, then on March 7, 2027 you are 8 weeks and 0 days pregnant, in the first trimester, and your due date is October 17, 2027, 224 days away.

Frequently asked questions

How many weeks pregnant am I?

Enter the first day of your last period, or your due date or conception date. The calculator counts the weeks and days from the start of the pregnancy to today.

Why does my doctor count weeks differently?

Providers may adjust your dating after an early ultrasound. If their date differs from this calculator, follow your provider.

When should I contact a doctor?

If you think you may be pregnant, take a test and contact a doctor or midwife to start prenatal care. For urgent symptoms, seek medical help right away.

What happens after the due date?

Many pregnancies continue past the due date. The calculator shows how many days past it you are, and your care team will advise you.

This calculator is for general information only and is not medical advice.