Due Date Calculator 🤰
Estimate when your baby is due and see how far along you are today.
This is an estimate based on a standard 40-week (280-day) pregnancy. Only about 1 in 20 babies arrive on the exact due date. Always confirm dates with your doctor — this tool is not medical advice.
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How your due date is calculated
The standard estimate, known as Naegele's rule, adds 280 days (40 weeks) to the first day of your last menstrual period, assuming a regular 28-day cycle with ovulation around day 14. That is why a due date can shift slightly if your cycles are longer, shorter, or irregular, and why an early-pregnancy dating scan is considered more accurate than the period date alone.
What the weeks mean and what comes next
Your due date marks roughly 40 weeks, but full-term is a four-week window from 37 to 42 weeks, so treat the date as a guide rather than a guarantee. If you are not sure when you ovulated, our ovulation calculator can help, and once you have your date you can follow each stage with our week-by-week pregnancy guide. Always confirm your dating and any concerns with your doctor or midwife.
FAQs
- How accurate is a due date?
- A due date is an estimate, not a deadline. Only about 1 in 20 babies arrive on their exact due date, and a full-term birth is anywhere from 37 to 42 weeks. An early-pregnancy ultrasound gives the most accurate dating.
- Why is pregnancy counted from my last period?
- Because the exact day of conception is usually unknown, pregnancy is counted from the first day of your last menstrual period (LMP). That is why you are considered about two weeks pregnant at the moment of conception.