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Pregnancy Due Date Calculator — From Last Period or Conception
Estimate your pregnancy due date using the standard obstetric method — 280 days (40 weeks) from the first day of your last menstrual period, or adjusted from a known conception date — the same estimate a healthcare provider's initial calculation is typically based on.
How to use Due Date Calc
- Enter the first day of your last period, or your conception date.
- Read the estimated due date.
- See how many weeks along you currently are.
Frequently asked questions
- How accurate is this estimate?
- It gives the standard 40-week estimate used as a starting point; only about 5% of babies arrive exactly on the calculated date, and an ultrasound dating scan generally refines the estimate further.
- Why 280 days from the last period instead of conception?
- Conception date is often unknown, while the last period date usually is — the standard convention counts from it and assumes ovulation around day 14, which is why a conception-based estimate can differ slightly.
- Is my information stored anywhere?
- No. The calculation runs entirely in your browser and nothing is saved or transmitted.
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