Free tool
Due date calculator
Enter your last period — or a due date you already have — to see your estimated due date, how many weeks along you are, your trimester, and what’s happening this week.
Common questions
How is my due date calculated?
The standard method (Naegele’s rule) counts 280 days — 40 weeks — from the first day of your last menstrual period. If you know your due date, we work backwards the same way. An early ultrasound is the most accurate dating and may shift this estimate by a few days.
How many weeks pregnant am I?
Pregnancy is counted in weeks from the first day of your last period, so you’re already considered ~2 weeks pregnant at conception. Enter your last period date above and we’ll show your current week and day.
Is the calculator a substitute for my provider?
No. It’s a quick estimate. Your obstetric provider’s dating — especially from an early scan — is the number to go by for appointments and decisions.