Pregnancy Week & Due Date Calculator
Find how many weeks and days pregnant you are and your due date from your last period, conception date or an ultrasound dating.
Loading the tool…
User reviews
No reviews yet. If you’ve used this tool, be the first to leave one.
How to use
Everything you enter is processed only in this browser.
Choose what you know: last period, conception date or ultrasound weeks
Enter the date
Check the pregnancy week, due date and key milestone dates
How it works and good to know
By Naegele’s rule, the due date = first day of last period + 280 days (40 weeks), shifted by the difference if your average cycle isn’t 28 days. From the conception date it’s + 266 days; from an ultrasound, the weeks on the scan date are subtracted to get the last period date. The first trimester runs through 13 weeks 6 days, the second through 27 weeks 6 days, the third from week 28, and full term from 37 weeks 0 days. These are reference values; follow your doctor’s due date. Inputs aren’t saved.