Pregnancy due-date estimator

How this estimator works

This tool starts with the first day of your last period and estimates a due date around 40 weeks later . If your usual cycle is longer or shorter than 28 days, it adjusts the estimate slightly to account for later or earlier ovulation.

Why dates can change

Due dates are estimates, not deadlines. Early ultrasound dating, cycle irregularity, and not knowing the exact last-period date can all shift the most accurate estimate.

When to confirm with a clinician

If you have a positive pregnancy test, unusual pain, bleeding, or uncertainty about dates, book prenatal care. A clinician can confirm dating and check that everything is progressing safely.

Frequently asked questions

Is this my official due date?

No. It is an educational estimate. Your clinician may update your due date after an ultrasound or clinical review.

What if my cycle is not 28 days?

Use your usual cycle length. The estimator adjusts the due date based on the difference between your cycle and a 28-day cycle.

Can I use this if I conceived with IVF?

IVF due dates are usually calculated from embryo transfer and embryo age, so a last-period estimator is not the best fit. Use your clinic's date.

Is my data saved?

No. The estimate runs in your browser and is not saved when you leave the page.

Important disclaimer

This estimate is educational and does not replace prenatal care. Ultrasound dating and your clinician's assessment are more accurate.