Pregnancy Due Date Calculator
Estimate your due date and how far along you are from the first day of your last menstrual period.
Calculating…
How it works
Naegele's rule: due date = first day of last period + 280 days (40 weeks), adjusted for cycles longer or shorter than 28 days.
Only a small share of babies arrive exactly on the due date. An ultrasound gives a more precise estimate.
Tips
- Your doctor or midwife may adjust your due date after an early ultrasound.
- Write down your period dates. They're the first thing you'll be asked.
Frequently asked questions
Why is pregnancy counted from my last period?
Because that date is usually known, while the exact conception date usually isn't. It adds about two weeks before conception.
For general information only. Not medical advice — talk to a doctor or other qualified professional about your health.