HEALTH TOOL
Pregnancy Due Date Calculator
Estimate a due date and current week of pregnancy from the last menstrual period.
Defaults to 28 days — adjust if your cycle is typically longer or shorter.
Estimated due date
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Current stage (as of today)
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About this tool
Estimates a due date using Naegele's rule — the standard method of counting 280 days (40 weeks) from the first day of the last menstrual period, adjusted if a cycle length other than 28 days is entered. It also shows how many weeks and days along the pregnancy is as of today.
This is a general estimate, not a medical diagnosis. Actual due dates are best confirmed and tracked with an ultrasound and a healthcare provider, since ovulation timing varies between cycles and people.
Frequently asked questions
- How accurate is this estimate?
- Naegele's rule is a widely used starting estimate, but only around 5% of babies arrive exactly on the calculated due date — a full-term range of about three weeks before to two weeks after is considered normal.
- Why does cycle length matter?
- The standard 280-day calculation assumes a 28-day cycle with ovulation around day 14. A longer or shorter average cycle shifts the likely ovulation date, so the estimate adjusts accordingly.
- What if I don't know my last menstrual period date?
- An ultrasound-based dating estimate from a healthcare provider is more reliable in that case — this tool depends on that date being reasonably accurate.