Wondering when your little one will arrive? Our free due date calculator estimates your due date, how far along you are, your current trimester, and how many days you have left — based on your last period, conception date, or IVF transfer. Just pick a method and date below.

This estimate is for general guidance only and is not medical advice. Only about 1 in 20 babies arrive on their exact due date — most arrive within a week or two either side. Your provider’s dating is definitive.

How Is My Due Date Calculated?

The most common method is Naegele’s rule: your estimated due date is about 280 days (40 weeks) from the first day of your last menstrual period (LMP). If you know your conception or ovulation date, we count 266 days from there instead. For IVF, we count from the transfer date based on the embryo’s age. If your cycle is longer or shorter than the typical 28 days, the calculator adjusts your estimate accordingly.

Remember: a due date is an estimate, not a deadline. A full-term baby can safely arrive any time between 37 and 42 weeks, and only about 5% are born on their exact due date. Your provider’s dating ultrasound is the most accurate measure.

What to Do Next

Frequently Asked Questions

How accurate is a due date calculator?

It gives a solid estimate, but only about 1 in 20 babies are born on their exact due date. Most arrive within two weeks before or after. An early dating ultrasound (before ~13 weeks) is the most accurate way to confirm your due date.

Can I calculate my due date from conception?

Yes. If you know your conception or ovulation date, select “Conception date” and we count 266 days forward. This can be more precise than the last-period method if your cycle is irregular.

How many weeks pregnant am I?

Pregnancy is counted in weeks from the first day of your last period, so you are typically considered about 2 weeks “pregnant” at conception. The calculator shows your current weeks and days, plus which trimester you are in.