Pregnancy Due Date Calculator
Estimate your due date and how far along you are. Runs entirely in your browser. Nothing you type is ever uploaded. This is an estimate, not medical advice.
What can you calculate?
DueDate estimates an expected due date and how far along a pregnancy is today, calculated from either the first day of the last menstrual period (with an adjustment for cycle length) or a known conception date.
Wondering how accurate a due date actually is? Read Why Only About 5% of Babies Arrive on Their Due Date.
How it works
Every calculation runs directly in your browser using standard date arithmetic. Nothing is sent to a server, so it works even offline once the page has loaded.
Frequently asked questions
Is this free to use?
Yes. There's no sign-up and no limit on how many calculations you run.
Do you store what I type?
No. Every calculation happens entirely client-side in your browser. See the privacy policy for details.
How is the due date calculated?
From the last menstrual period, it uses Naegele's rule: adding 280 days (40 weeks), adjusted for a cycle length other than 28 days. From a conception date, it adds 266 days (38 weeks), since conception typically occurs about two weeks after the last period.
Is this accurate?
It's a widely-used estimation method, not a diagnosis. Only about 5% of babies are actually born on their calculated due date, and a full-term range spans roughly two weeks either side of it. An ultrasound dating scan from your care provider is more accurate than a date-based estimate alone.