Pregnancy Due Date Calculator

Enter the first day of your last period — get the estimated due date, current week and trimester timeline.

Quick answer: Free pregnancy due date calculator: estimated due date from your last period, current week, trimester dates. Based on Naegele's rule.

Estimated due date
Current week
Trimester
Conception ≈

Medical estimate only — always confirm with your healthcare provider.

How to use

  1. Open this page on any device — no signup needed.
  2. Fill in the fields above.
  3. Get your result instantly — nothing is uploaded.

About this tool

The standard due-date estimate (Naegele's rule) adds 280 days to the first day of the last menstrual period, adjusted for cycle length. Only about 4% of babies arrive exactly on the due date — full term spans week 37 to 42. This tool also shows your current gestational week and trimester boundaries. It is an estimate, not medical advice.

FAQ

How accurate is the due date?
It is an estimate; most babies arrive between 37–42 weeks. Your doctor's ultrasound dating is the gold standard.
My cycle is longer than 28 days — does that matter?
Slightly — ovulation likely happened later. The calculator adjusts by your cycle length.
When does each trimester start?
First: week 1–13, second: week 14–27, third: week 28–birth.