Pregnancy Week Calculator
Pregnancy Week Calculator shows how many weeks and days pregnant you are, your current trimester, a progress ring to 40 weeks, and the estimated size of your baby.
Last updated: July 2026
A pregnancy week calculator tells you how far along you are in weeks and days (gestational age), which trimester you're in, and how long until your due date, based on the first day of your last period.
How to use Pregnancy Week Calculator
- Enter the first day of your last menstrual period (or your known due date).
- The calculator works out your gestational age in weeks and days.
- Read your trimester, progress and estimated due date.
Frequently asked questions
How is pregnancy dated?
Gestational age is counted from the first day of your last menstrual period (LMP), so week 1 begins about two weeks before conception.
How accurate is it?
It's based on a standard 40-week pregnancy from LMP. Your provider's ultrasound dating may differ slightly.
Is my data private?
Yes — all calculations run in your browser.
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