About Pregnancy Calculator

Estimates pregnancy progress and due date using either the last menstrual period (LMP) or a known conception date. Calculates the standard 280-day (40-week) gestation, determines the current trimester, and tracks 13 developmental milestones from missed period through delivery. Displays a progress bar, trimester date ranges, and supports calculation history with CSV export.

• Two input modes: LMP-based (adds 280 days) or conception-based (subtracts 14 days to derive LMP)
• Real-time display of weeks + days pregnant, days remaining, and percent complete
• Trimester boundaries: 1st (weeks 0–12), 2nd (weeks 13–26), 3rd (weeks 27–40)
• Milestone tracker covering heart beat (week 6), viability (week 24), full-term (week 37), and more
• Calculation history stores up to 10 entries, exportable as CSV

Frequently Asked Questions

How accurate is the due date calculation?

It uses Naegele’s rule: LMP + 280 days. This assumes a 28-day cycle with ovulation on day 14. Only about 5% of babies arrive on the exact due date—normal delivery ranges from 37 to 42 weeks. An ultrasound-based estimate from your provider will be more precise.

What does the conception date mode assume?

It back-calculates the LMP by subtracting 14 days from the conception date you provide, then applies the standard 280-day formula from that derived LMP. This mode is useful for IVF patients or anyone who knows their exact ovulation date.