The first thing you want to know
Due Date Calculator
One date is all it takes. You'll get your due date, exactly how far along you are today, and what's coming next. Already know your due date? Start from that instead.
This is general information, not medical advice. Every pregnancy is different, and yours is the one your provider knows.
Where that date comes from
The standard method counts 280 days from the first day of your last menstrual period. That's 40 weeks, and it's how your provider will date your pregnancy too.
It builds in an assumption: that you ovulated on day 14 of a 28-day cycle. If your cycles run longer or shorter than that, you ovulated later or earlier, and your due date shifts with it — which is why this calculator asks. If you're working from a known conception date, it counts 266 days instead, since conception happens about two weeks after a period starts.
You may have seen the shorthand taught as Naegele's rule: take your last period, add seven days, subtract three months, add a year. That's a good mental estimate, but it treats every month as the same length, so it can land up to three days off a true 280-day count. This calculator counts the actual days.
Whatever number you get here, a due date is a midpoint, not a deadline. Only about 1 in 20 babies arrive on it. If your provider has dated your pregnancy from a first-trimester ultrasound, use their date — early scans are the most accurate dating there is.
Want the longer version? Read how due dates are calculated, including what ultrasound dating changes and what "full term" actually means.
While you're here
How is a due date calculated?
The standard method counts 280 days — 40 weeks — from the first day of your last menstrual period. If you know your conception date instead, it's 266 days from there.
How accurate is a due date?
About 1 in 20 babies arrive on their due date. It is an estimate of a range, not a scheduled appointment — anything from 37 to 41 weeks is considered normal timing.
What if my cycle is not 28 days?
A longer cycle means you ovulated later, so your due date moves later too. This calculator adjusts for cycle length, which the standard 280-day count does not.
Is an ultrasound due date more accurate than one from my last period?
Usually yes, especially a first-trimester scan, which can date a pregnancy within a few days. If your provider gave you a date from a scan, use theirs.