How Due Date Calculation Works
1
Last Menstrual Period
We use the first day of your last period as the starting point for pregnancy calculation.
2
Naegele's Rule
Add 280 days (40 weeks) to your LMP date to get your estimated due date.
3
Trimester Calculation
Pregnancy is divided into three trimesters of approximately 13-14 weeks each.
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This calculator runs entirely in your browser. No data is sent to our servers or stored anywhere. Your personal information stays private.
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