Pregnancy Due Date Calculator

How to Use Pregnancy Due Date Calculator

1. Select your method. Choose either "Last Menstrual Period (LMP)" or "Conception Date" from the dropdown – whichever you know more accurately.
2. Enter the date and cycle length. For LMP, pick the first day of your last period and set your usual cycle length (21‑35 days). For conception, input the known date.
3. Click Calculate. The tool instantly applies Naegele’s rule (LMP + 280 days + cycle adjustment) or the 266‑day formula for conception.
4. Review your results. You’ll see your estimated due date, current pregnancy week, trimester, days remaining, and milestone dates for each trimester.

Benefits of Pregnancy Due Date Calculator

• Two calculation modes adapt to the information you have, making it useful for both natural and assisted pregnancies.
• Cycle‑length adjustment gives a more personalised due date than a generic 28‑day assumption.
• Immediate trimester and milestone dates help you plan prenatal visits and prepare for each stage.
• No need to download an app – use it on any device with a browser, completely offline once loaded.

Frequently Asked Questions

How accurate is the pregnancy due date calculator?

It provides a solid estimate, but only about 4% of babies arrive exactly on the due date. Early ultrasound dating is the most accurate method; this calculator uses standard obstetric formulas.

Can I use the calculator if my cycle is irregular?

You can, but the result will be less precise. Enter your average cycle length and consider the due date as a rough guideline; a dating scan will give a more reliable date.

What if I don’t know my LMP or conception date?

If both dates are uncertain, an early ultrasound is the best way to date the pregnancy. The calculator works best when you have at least one of these reference points.

Is Pregnancy Due Date Calculator free and private?

Yes — it is 100% free, needs no sign‑up, and everything runs in your browser; your data never leaves your device.