Pregnancy Weeks Converter
Convert pregnancy weeks to months, trimesters, and days with due date calculator
Gestational Age
20w 0d
Trimester 2
Baby is about the size of a Banana
Total Days
140
Calendar Months
4.6
Lunar Months
5
Days Remaining
140
Upcoming Milestones
Week Quick Select
Weeks to Months Conversion
| Weeks | Months | Trimester |
|---|---|---|
| Weeks 1-4 | Month 1 | 1st Trimester |
| Weeks 5-8 | Month 2 | 1st Trimester |
| Weeks 9-12 | Month 3 | 1st Trimester |
| Weeks 13-17 | Month 4 | 2nd Trimester |
| Weeks 18-22 | Month 5 | 2nd Trimester |
| Weeks 23-27 | Month 6 | 2nd Trimester |
| Weeks 28-31 | Month 7 | 3rd Trimester |
| Weeks 32-35 | Month 8 | 3rd Trimester |
| Weeks 36-40 | Month 9 | 3rd Trimester |
Understanding Pregnancy Dating
Gestational age is calculated from the first day of the last menstrual period (LMP), about 2 weeks before conception actually occurs.
Full term is considered 39-40 weeks. Births at 37-38 weeks are "early term," and 41+ weeks are "late term."
Due date accuracy: Only about 5% of babies are born on their exact due date. Most arrive within 2 weeks before or after.
Note: This calculator is for informational purposes only. Consult your healthcare provider for accurate pregnancy dating.
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Editorial Note
MyCalcBuddy Editorial Team
This page is maintained as an educational calculator reference.
Formula Source: NIST Guide to SI Units
by National Institute of Standards