How does the pregnancy due date calculator work?

The calculator estimates the estimated due date, gestational age, estimated conception date, and calculated LMP using pregnancy dating methods such as LMP, ultrasound, EDD, IVF transfer data, or conception date.

Is the result based on standard obstetric dating?

Yes. The page uses common obstetric dating conventions, including the 280-day pregnancy model from LMP and the 266-day model from conception.

Can ultrasound dating override the LMP estimate?

Yes. Ultrasound dating can provide a more precise estimate when the scan date and measured gestational age are known.

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Pregnancy Due Date & Milestone Calculator

Estimate your due date, gestational age, conception timing, and pregnancy milestones with a refined medical-grade interface. Switch seamlessly between LMP, ultrasound, known EDD, IVF / ART, and conception date methods.

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EDD model

280 days

Conception model

266 days

Average singleton

39 weeks

Warm mother and baby medical lifestyle scene

Real image

A gentle, premium visual anchored in a real mother-and-baby lifestyle photograph.

LMP First DayCycle Length

Calculation method

LMP • Instant front-end calculation

Pregnancy milestones

Week 8

Embryonic heartbeat often visible on ultrasound

Feb 26, 2026

Week 12

First trimester screening window

Mar 26, 2026

Week 20

Anatomy scan milestone

May 21, 2026

Week 24

Viability threshold period

Jun 18, 2026

Week 28

Third trimester begins

Jul 16, 2026

Week 36

Baby often moves into head-down position

Sep 10, 2026

Week 39

Average singleton delivery window

Oct 1, 2026

Week 40

Estimated due date

Oct 8, 2026

Result panel

Estimated Due Date (EDD)

October 8, 2026

Gestational Age

21 weeks 2 days

Calculated LMP

January 1, 2026

Estimated Conception Date

January 15, 2026

Pregnancy type comparison

Type	Average delivery week
Singleton	39 weeks
Twins	35 weeks
Triplets	32 weeks

How this was derived

Standard obstetric dating assumes a 280-day pregnancy from the first day of the corrected LMP and a 266-day interval from conception to estimated delivery.

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FAQ

Common questions about pregnancy dating

These answers are optimized for search visibility and explain the logic behind the calculator in clear English.

What is the difference between LMP dating and conception dating?

LMP dating starts from the first day of the last menstrual period and typically uses a 280-day pregnancy model. Conception dating starts from the estimated day of fertilization and typically uses a 266-day model.

How does the ultrasound method calculate EDD?

The calculator subtracts the measured gestational age from 40 weeks on the scan date, then projects the remaining days forward to estimate the due date.

Why does IVF use embryo transfer date?

IVF dating is usually based on transfer timing plus embryo age to estimate conception timing, then it applies the standard 266-day conception-to-delivery interval.

Can this page help track pregnancy milestones?

Yes. The page highlights key milestone weeks such as first trimester screening, anatomy scan, viability, third trimester, and the average delivery window.