How to Calculate Your Pregnancy Due Date

Published 5 November 2026 by Kloora Tools

Quick answer: use the free Pregnancy Due Date Calculator to estimate your due date and current week of pregnancy from the first day of your last period. It runs in your browser, so nothing you enter is uploaded or stored, and there is no signup.

What is the Pregnancy Due Date Calculator?

Estimate your due date and current week of pregnancy from the first day of your last period. People often search for it as "due date calculator", "pregnancy due date calculator" or "pregnancy calculator". This free version works on any phone or computer and needs no download.

How to use the Pregnancy Due Date Calculator

Open the Pregnancy Due Date Calculator.
Enter your values in the fields.
The results update instantly as you type.
Note or copy the numbers you need.

How it works

Naegele rule: add 280 days (40 weeks) to the first day of your last menstrual period. The tool also shows how many weeks pregnant you are today and which trimester you are in. Only a scan can confirm the date, and most babies arrive within two weeks of it.

Worked example

Input: First day of last period: 2026-06-01
Result: Estimated due date: Mon Mar 08 2027; Now: 21 weeks, 4 days; Trimester: Second

Common uses

Estimate a due date before the first appointment
Find out how many weeks pregnant you are
Plan leave and preparations

Tips for the best result

Measure yourself the same way each time, ideally in the morning and before eating.
Use the result as a guide and look at the trend over weeks, not a single day.
Choose the activity level honestly, because most people overestimate it.
Talk to a doctor or a qualified coach before making big changes to diet or training.

Common mistakes to avoid

Entering pounds or inches in a field that expects kilograms or centimetres.
Treating an estimate as a medical diagnosis.
Comparing your result with someone of a different age, sex or build.
Changing several things at once, so you cannot tell what worked.

Pregnancy Due Date Calculator compared with doing it by hand

	Pregnancy Due Date Calculator	By hand or in a spreadsheet
Speed	Instant, results update as you type	Slow, you rebuild the steps each time
Accuracy	Same standard method every time	Easy to slip on a formula or a unit
Privacy	Runs in your browser, nothing uploaded	Depends on the software you use
Cost	Free, no signup	Free or paid software needed

Try it now

Open the Pregnancy Due Date Calculator and try your own numbers or text. If it helps, share it with someone who needs it.

Try it now: Pregnancy Due Date Calculator. Estimate your due date and current week of pregnancy from the first day of your last period.

Frequently asked questions

How is the due date calculated?

Naegele rule: add 280 days (40 weeks) to the first day of the last menstrual period.

Is the due date exact?

No. Only about 5 percent of babies arrive on the due date. A doctor can confirm with a scan.

What does the Pregnancy Due Date Calculator do?

Estimate your due date and current week of pregnancy from the first day of your last period.

How do I use the Pregnancy Due Date Calculator?

1. Enter your values in the fields. 2. The results update instantly as you type. 3. Note or copy the numbers you need.

Is my data safe when I use the Pregnancy Due Date Calculator?

Yes. Everything runs in your browser on your own device. Nothing you type or choose is uploaded, stored or shared, and no AI service is used.

Does the Pregnancy Due Date Calculator work on a phone?

Yes. It works on phones, tablets and computers in any modern browser, with nothing to install.

Do I need an account or a payment to use the Pregnancy Due Date Calculator?

No. It is free, has no daily limit, no watermark and needs no signup.

What information does the Pregnancy Due Date Calculator need?

You enter: First day of last period. The results update instantly as you change any value.

How does the Pregnancy Due Date Calculator work?

Naegele rule: add 280 days (40 weeks) to the first day of your last menstrual period.

Can I use this for "pregnancy due date calculator"?

Yes. The Pregnancy Due Date Calculator is built for exactly that, and it also answers searches such as "due date calculator" and "pregnancy calculator".

How accurate is the Pregnancy Due Date Calculator?

It uses the standard method and shows results to a sensible precision. For legal, medical, financial or safety decisions, confirm important numbers with a qualified professional.

Where can I find more free tools like the Pregnancy Due Date Calculator?

Kloora Tools has over 150 free tools for CVs, PDFs, images, Urdu, calculators and everyday tasks. Browse them all from the home page.