Pregnancy Due Date Calculator
Estimate your due date and current week, based on your last period or a known conception date.
How this is estimated
From the last period, this uses Naegele's rule: 280 days (40 weeks) after that date, based on an average 28-day cycle. From a conception date, it adds 266 days (38 weeks) instead. Only about 5% of babies arrive exactly on the estimated date — it's a useful planning marker, not a precise prediction.
About the Pregnancy Due Date Calculator
The Pregnancy Due Date Calculator estimates your due date from the first day of your last period or from a conception date, and shows how far along you are. It is meant for planning and curiosity, not for medical decisions.
From the last period it uses Naegele's rule: 280 days (40 weeks) after that date, assuming a 28-day cycle. From a conception date it adds 266 days (38 weeks). Only a small share of babies arrive on the estimated date. An early ultrasound is usually a more accurate way to date a pregnancy, and your doctor or midwife will confirm the date.
How to use it
- Choose whether to calculate from your last period or from conception.
- Enter the date.
- Read the due date and current week.
- Discuss the date with your healthcare provider.
Tips and good to know
- If your cycle is irregular, the estimate may be off.
- Babies born between 37 and 42 weeks are considered normal term.
- Keep appointments for scans.
Frequently asked questions
How accurate is the due date?
It is an estimate.
Why 280 days?
It is 40 weeks, counted from the last period.
Is this medical advice?
No.