Pregnancy Due Date Calculator
Estimated due date
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1st trimester ends
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2nd trimester ends
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Full term (40 wks)
Estimate only - your doctor confirms dates by ultrasound. Not medical advice.
About this tool
Estimate your due date from your last period — plus weeks pregnant today and trimester dates.
Enter the first day of your last menstrual period (and your average cycle length) to estimate your due date using the standard 280-day rule, adjusted for your cycle. You also see how many weeks pregnant you are today and when each trimester begins and ends.
Roughly 1 in 20 babies arrives on the exact due date — treat it as the center of a window. Your doctor will confirm dating by ultrasound; this is not medical advice.
How to use
- Pick the first day of your last period.
- Adjust cycle length if it isn't 28 days.
- Read the due date, current week and trimester dates.
Frequently asked questions
Naegele's rule: LMP + 280 days, adjusted by (cycle length − 28) for longer or shorter cycles.
Only ~5% of babies arrive on the exact date; most arrive within two weeks either side. Early ultrasound dating is more precise.
An early ultrasound gives the best estimate — ask your care provider.