Pregnancy Due Date Calculator — When Is Your Baby Due?

First day of your last period (LMP) The first day bleeding started — not the day it ended.

Your estimated due date

Pregnancy completed0%

How far along

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Trimester

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Days to go

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Estimated conception

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Around 14 days after your last period.

This is an estimate only, based on a typical 28-day cycle — it is not medical advice. Only a scan and your doctor or midwife can date a pregnancy properly, so please confirm your dates with them.

How it works

Three quick steps — no account, no upload, nothing leaves your device.

Enter your last period date

Pick the first day of your most recent period — the day bleeding started.

Get your due date

Your estimated due date appears instantly, worked out as 280 days (40 weeks) from that date.

See where you are today

How many weeks along you are, your trimester, a progress bar and how many days remain — all updated to today.

Frequently asked questions

Quick answers about how this calculator works.

How is the due date calculated?

By Naegele's rule, the standard method used worldwide: add 280 days (40 weeks) to the first day of your last menstrual period. It assumes a regular 28-day cycle with conception about 14 days after the period started.

My cycle is not 28 days — is the date still right?

It will be close, but longer cycles usually mean a slightly later due date and shorter cycles a slightly earlier one. An early ultrasound scan gives the most accurate dating, which is why your doctor or midwife may adjust this date.

Which trimester am I in?

The first trimester runs to the end of week 13, the second from week 14 to week 27, and the third from week 28 until your baby is born. This page works yours out from how many weeks along you are today.

What if the due date has passed?

That is very common — only about 1 in 20 babies arrives on the exact date. Most arrive within two weeks either side. If you pass your date, your care team will talk you through what happens next.

Is my data private?

Completely. Everything runs in your browser — your dates are never uploaded, stored, or shared.