Part of the topic: 👶 Family & children
Pregnancy week & due date calculator
Enter the first day of your last period and your usual cycle length. Your doctor's ultrasound date always takes precedence.
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🔒 Runs entirely in your browser – nothing you enter is uploaded or stored.
How to use it
- Enter the first day of your last menstrual period.
- Adjust the cycle length if it is not 28 days.
- Read week of pregnancy, due date and the start of maternity protection.
Last checked: October 2026 · Based on: Naegele's rule; § 3 German Maternity Protection Act. Found a mistake? Use the form below – we fix confirmed errors and update the date.
Frequently asked questions
How is the due date calculated?
With the Naegele rule: first day of the last period + 280 days (40 weeks), corrected for longer or shorter cycles.
What does 12+3 mean?
12 completed weeks of pregnancy plus 3 days – you are in the 13th week.
When does maternity protection start?
Six weeks before the calculated due date (§ 3 MuSchG); after birth it usually lasts eight weeks.