Pregnancy Due Date Calculator
Estimated due date and milestones
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About this calculator
A typical pregnancy lasts about 40 weeks (280 days) from the first day of the last menstrual period. The calculator adjusts for cycle length and shows the current week and trimester milestones.
The formula
Due date = first day of last period + 280 days (adjusted for cycle length)
Worked exampleLMP 1 January with a 28-day cycle → due date 8 October.
Frequently asked questions
How accurate is a due date?
Only about 4–5% of babies arrive on the exact day. Most are born within two weeks either side.
What if my cycle is not 28 days?
Enter your usual length; the date shifts by the difference.
Is this medical advice?
No. Your midwife or doctor will confirm dates with a scan.
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