How accurate is the LMP method?

It assumes a 28-day cycle and ovulation on day 14. Ultrasound dating in the 1st trimester is more accurate.

Pregnancy is split into three trimesters of ~13 weeks each.

Health

Gestational Age Calculator

Calculate precise gestational weeks, days, and trimester

First day of Last Menstrual Period (LMP)

Today is 09 Jul 2026.

Estimated Due Date

14 Feb 2027

8 weeks 4 days · Trimester 1

Current Week

Days Pregnant

Days to Due Date

220

Trimester

Formula

EDD (Naegele's rule) = LMP + 280 days (40 weeks)

Example: LMP on 1 Jan 2026 → EDD ≈ 8 Oct 2026.

How to use

Pick the first day of your last menstrual period.
View your due date, current week and trimester.

Benefits

Track pregnancy milestones week by week.
Plan prenatal appointments and tests.

Frequently Asked Questions

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This is NOT medical advice. Always consult your obstetrician for any concerns about your pregnancy.

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How accurate is the LMP method?

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Gestational Age Calculator

Formula

How to use

Benefits

Frequently Asked Questions

How accurate is the LMP method?

What is a trimester?

Related Calculators