Pregnancy Weeks Converter
Convert pregnancy weeks and days to months and trimester.
Calculate your due date from last period.
Your data stays in your browser. We do not store, collect, or transmit any information you enter.
Pregnancy is measured from the first day of the last menstrual period (LMP). Full term is typically 40 weeks (280 days).
Weeks to months (approximate):
- Weeks 1-4: Month 1
- Weeks 5-8: Month 2
- Weeks 9-13: Month 3
- Weeks 14-17: Month 4
- Weeks 18-22: Month 5
- Weeks 23-27: Month 6
- Weeks 28-31: Month 7
- Weeks 32-35: Month 8
- Weeks 36-40: Month 9
Trimesters:
- First trimester: Weeks 1-12
- Second trimester: Weeks 13-27
- Third trimester: Weeks 28-40
Due date calculation: Due date = LMP date + 280 days (Naegele’s rule). This is the same as LMP + 40 weeks.
Note: Every pregnancy is unique. These are standard medical approximations.