Calculators
Pregnancy Due Date Calculator
Estimate your due date from your last period — plus weeks pregnant today and trimester dates.
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
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.