Pregnancy Due Date Calculator
Due date & pregnancy week
| Milestone | Date |
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This is an estimate for information only. Your doctor or midwife may adjust your due date after an ultrasound.
About the Pregnancy Due Date Calculator
Your estimated due date (EDD) is usually calculated as 280 days (40 weeks) from the first day of your last menstrual period. This calculator works from your last period, adjusting for your cycle length, or from a known conception date, and shows how far along you are today.
- Choose your last period or your conception date.
- Enter the date and, for LMP, your usual cycle length.
- See your estimated due date, current week, trimester and key milestones.
Frequently asked
How is the due date calculated?
It uses Naegele's rule: the first day of your last period plus 280 days, adjusted by the difference between your cycle length and 28 days.
How accurate is a due date?
Only about 4–5% of babies arrive exactly on their due date. Most are born within two weeks either side. An early ultrasound gives the most accurate date.
Is this medical advice?
No. It is an estimate for information only. Always follow the guidance of your doctor or midwife.
Is what I type sent to a server?
No. The tool runs entirely in your browser and there's no server behind it, so what you type never leaves your device and nothing is stored. You can check: it keeps working if you go offline after the page has loaded.
More from the Calculators drawer
Other tools kept in this drawer, plus a few favourites from the bench.