🤰 Pregnancy Due Date Calculator
Estimate a due date from the last menstrual period.
About this tool
Estimates an approximate due date using the standard 280-day (40-week) method based on the first day of your last menstrual period — the same estimate method commonly used as a starting reference point.
Once you have a due date, the Date Difference Calculator can tell you exactly how many days remain until it.
Worked example
If the first day of your last period was March 1, 2026, the estimated due date works out to around December 6, 2026, using the standard 280-day method.
How to use it
- Enter the first day of your last menstrual period.
- Press Calculate.
- See your estimated due date.
Tips
- This is an estimate based on a standard 40-week cycle — actual due dates vary and your provider may adjust it based on an ultrasound.
- Only about 5% of babies are born exactly on their estimated due date — treat it as a window, not a fixed day.
- Always confirm with a healthcare provider, who may use additional information for a more precise estimate.
FAQ
How accurate is this method?
It's a standard estimation method, but actual delivery dates commonly vary by a week or two in either direction.
What if I don't know my exact last period date?
An ultrasound-based estimate from a healthcare provider will be more accurate than this calculator.
Is this medical advice?
No — this is a general estimate tool, not a substitute for care from a healthcare provider.