Pregnancy Due Date Calculator
Estimate your baby's arrival date
days
Estimated Due Date
—
Current Week
—
Trimester
—
Days Remaining
—

What is the pregnancy due date calculator?

A pregnancy due date calculator estimates your Estimated Due Date (EDD) — when your baby is expected to arrive — based on your last menstrual period (LMP) or conception date. A full-term pregnancy lasts approximately 40 weeks (280 days) from the first day of the last period.

Formula used

Naegele's Rule (standard method): EDD = First day of LMP + 280 days Adjusted for cycle length: EDD = LMP + 280 + (cycle length − 28) days Trimester boundaries: First: Weeks 1–13 Second: Weeks 14–27 Third: Weeks 28–40+

How to use this calculator

  1. Select LMP method or Conception date method
  2. Enter the date (first day of last period, or conception date)
  3. Adjust cycle length if different from 28 days
  4. Click Calculate — see due date, current week, trimester, and days remaining

Example

Example — Standard 28-day cycle:
LMP: 1 January 2025 | Cycle: 28 days
EDD = 1 Jan + 280 days = 8 October 2025

Example — Longer cycle (32 days):
LMP: 1 January 2025 | Cycle: 32 days
EDD = 1 Jan + 280 + (32−28) = 1 Jan + 284 = 12 October 2025

Pregnancy milestones:

WeekMilestone
Week 6–8Heartbeat detectable by ultrasound
Week 12End of first trimester, risk of miscarriage drops significantly
Week 20Anatomy scan / gender can be determined
Week 37Full term — safe for delivery
Week 40Due date

Frequently asked questions

The calculator gives an estimate using Naegele's Rule. Only about 5% of babies arrive on their exact due date. A normal birth can occur anywhere from week 37 to 42. A first-trimester ultrasound provides the most accurate dating.
Use the Conception date method if you know approximately when you conceived — for example, from ovulation tracking, IVF transfer date, or an early positive test.
Yes. Your doctor may revise the EDD after a dating ultrasound, especially if it differs by more than 5–7 days from the LMP calculation.