What tips should I keep in mind?

Only 5% of babies arrive on their exact due date -- it is an estimate First pregnancies tend to go slightly past the due date Your doctor may adjust the due date after an early ultrasound

Due Date Calculator

Calculate your estimated due date from your last menstrual period or conception date. Uses Naegele's rule adjusted for cycle length.

Results

Visualization

How It Works

Pregnancy typically lasts 280 days (40 weeks) from the first day of your last menstrual period. This calculator uses Naegele's rule, adjusted for your cycle length. Not medical advice -- consult your doctor.

The Formula

Due Date = LMP + 280 days (adjusted for cycle length)
If cycle differs from 28 days, add/subtract the difference

Variables

LMP — First day of last menstrual period
280 — Standard pregnancy duration in days (40 weeks)
Cycle adj. — Difference from 28-day cycle added to EDD

Example

LMP was 60 days ago with a 28-day cycle = 8 weeks 4 days pregnant, about 220 days to go.

Tips

Only 5% of babies arrive on their exact due date -- it is an estimate
First pregnancies tend to go slightly past the due date
Your doctor may adjust the due date after an early ultrasound
Full term is 39-40 weeks; early term is 37-38 weeks