Pregnancy Calculator
Calculate your due date, current trimester, and weeks pregnant based on your last menstrual period.
Estimated Due Date
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Current Weeks —
Trimester —
Est. Conception Date —
How to Use This Calculator
Enter the date of your last menstrual period (month, day, year). The calculator estimates your due date, current week of pregnancy, trimester, and approximate conception date.
Formula
Due Date = Last Menstrual Period + 280 days
Conception ≈ LMP + 14 days
Trimester 1: weeks 1-12 | Trimester 2: weeks 13-26 | Trimester 3: weeks 27-40
Conception ≈ LMP + 14 days
Trimester 1: weeks 1-12 | Trimester 2: weeks 13-26 | Trimester 3: weeks 27-40
Example
Example: LMP of January 15, 2026: Due date = October 22, 2026. Estimated conception: January 29, 2026.
Frequently Asked Questions
- The due date is estimated by adding 280 days (40 weeks) to the first day of your last menstrual period (LMP). This is known as Naegele's rule.
- Only about 5% of babies are born on their exact due date. Most deliveries occur within 2 weeks before or after the estimated date.
- First trimester: weeks 1-12. Second trimester: weeks 13-26. Third trimester: weeks 27-40.
- Conception typically occurs about 14 days after the first day of the last menstrual period, during ovulation.