Pregnancy timeline

Due Date Calculator

Use last menstrual period, conception date, or ultrasound measurements to estimate your due date, trimester, and upcoming checkups.

Input methods

40 weeks

Timeline

Instant

Update speed

1. Choose a calculation method

2. Enter your data

First day of last period

Cycle length (days)

Pregnancy snapshot

Enter the information above and tap “Calculate due date” to see your pregnancy snapshot.

Disclaimer

Due dates are estimates. Natural labor often occurs within ±2 weeks.
This tool does not replace medical advice. Always follow your obstetrician’s plan.
Seek immediate help if you notice bleeding, contractions, or abnormal fetal movement.

What is Due Date Calculator

Estimate the due date three ways: last menstrual period (Naegele's rule, LMP + 280 days with your cycle length correcting the result), conception date (+266 days) or an ultrasound week measurement. Get the EDD, current week, countdown to the big day, current trimester and a 40-week timeline.

How to use Due Date Calculator

Enter your last period date (or conception/ultrasound data) and cycle length
Submit to see the estimated due date and trimester
Browse fetal development notes and the checkup timeline

Frequently asked questions

How is the due date computed?

From LMP it uses the standard 280-day estimate adjusted for your cycle length; conception and ultrasound inputs are converted to the same timeline.

Does cycle length change the estimate?

Yes — the 280-day rule assumes ovulation on day 14 of a 28-day cycle. Each extra cycle day pushes the EDD one day later; the cycle-length input applies this correction automatically.

Which method should I trust if they disagree?

An early-pregnancy ultrasound estimate is generally the most precise and what clinicians rely on; the LMP method is a quick estimate for regular cycles. All results here are reference values, not medical conclusions.

Is this medical advice?

No — results are for reference only and cannot replace a doctor. Confirm dates with your prenatal care provider.

Is Due Date Calculator free?

Due Date Calculator is completely free — open the page and use every feature with no hidden charges.

Do I need to download or install Due Date Calculator?

No download or installation is needed. It is an online tool that runs in the browser on your phone, tablet and computer.

Do I need an account to use Due Date Calculator?

No. Use the tool right away — no account or sign-in required.

Does Due Date Calculator work on mobile?

Yes. The page is fully responsive and works on phones, tablets and desktop browsers.