Pregnancy Week Calculator

Free Pregnancy Week Calculator

Use this free pregnancy week calculator to instantly find out how many weeks and days pregnant you are, along with your current trimester, using either your last menstrual period or your known due date.

Pregnancy is typically tracked in weeks starting from the first day of your last menstrual period, even though conception usually occurs about two weeks later.

How to Use the Pregnancy Week Calculator

• Choose whether you know your last menstrual period or your due date.
• Select the relevant date.
• Click Calculate Pregnancy Week.
• View your current week, trimester, and days remaining instantly.

Features

• Works from either your last menstrual period or a known due date.
• Shows your exact current week and day of pregnancy.
• Shows which trimester you're currently in.
• Mobile-friendly with print, share, copy, and download options.

Frequently Asked Questions

How are pregnancy weeks counted?

Pregnancy weeks are counted from the first day of your last menstrual period, not from the date of conception, which typically occurs about two weeks later. This is the standard method used by doctors and midwives.

When does each trimester start?

The first trimester runs from week 1 to the end of week 13, the second trimester from week 14 to the end of week 27, and the third trimester from week 28 until birth.

Is this as accurate as an ultrasound?

No. This calculator gives a general estimate based on standard dating methods. Ultrasound measurements, especially in the first trimester, are generally considered more precise and may adjust your dates.

Is this calculator free?

Yes, this pregnancy week calculator is completely free to use with no sign-up required.

Related Calculators

Want to estimate your due date from scratch? Try our pregnancy due date calculator. Curious about your baby's age after birth? Check the baby age calculator. Want a live countdown to your due date? Use the countdown timer.