Conception Date Calculator

Conception date calculations are estimates based on population averages. Calendar-based methods (like this tool) are approximately 75% effective due to individual variation in ovulation timing. Only 30% of women ovulate exactly 14 days before their next period. For medical accuracy, ultrasound dating (±3-5 days in first trimester) is the clinical gold standard.

Due date calculation works backward from your estimated delivery date using established gestational periods. LMP (Last Menstrual Period) calculation estimates forward from your cycle start using your average cycle length. Both methods use the same underlying science but start from different known dates.

Many factors affect conception timing: irregular ovulation (even in regular cycles), cycle length variations, luteal phase defects, stress, illness, or medications. Individual variation means actual conception could occur 2-3 days earlier or later than calculated estimates.

Consult healthcare providers for: family planning requiring precise timing, irregular cycles (variation >7 days), fertility concerns, pregnancy confirmation, or high-risk pregnancies. Medical dating scans provide the most accurate gestational age assessment.

This tool estimates past conception dates, not future fertility. For family planning, the fertility window shows when conception likely occurred (6-day period ending on ovulation). For future planning, consider ovulation prediction kits or fertility tracking apps with real-time monitoring.