Pregnancy Conception Calculator
Calculate your conception date and fertile window based on your due date or last menstrual period
The Pregnancy Conception Calculator helps you determine when conception likely occurred based on your due date or last menstrual period. This tool provides estimates for conception date, fertile window, and implantation timing to help you understand your pregnancy timeline.
Calculate Conception Date
Conception Timeline
Conception Window
Important Dates
Fertile Window
Current Pregnancy Status
How to Use
1. Choose your calculation method (due date, LMP, or ultrasound)
2. Enter the relevant date information
3. For LMP method, provide your average cycle length
4. For ultrasound method, enter gestational age
5. Click "Calculate" to see your conception timeline
6. Review the conception window and important dates
Understanding Conception
What is Conception?
Conception occurs when a sperm fertilizes an egg, typically within 24 hours of ovulation. This usually happens in the fallopian tube.
Timing Factors:
Sperm can survive up to 5 days in the female reproductive tract, while an egg survives about 24 hours after ovulation.
Calculation Methods
Due Date Method:
Calculates backwards from your due date. Most accurate if due date is confirmed by early ultrasound.
LMP Method:
Uses your last menstrual period and cycle length. Assumes ovulation occurs 14 days before next period.
Ultrasound Method:
Most accurate method, especially when done in first trimester. Uses measured fetal size to determine gestational age.
Important Timeline
Day 0: Last menstrual period begins
Day 14: Ovulation (in 28-day cycle)
Day 14-15: Conception window
Day 20-24: Implantation occurs
Day 28: Missed period
Day 280: Due date (40 weeks from LMP)
Accuracy Notes
• Conception date estimates have a margin of error of ±3-5 days
• Early ultrasound (6-10 weeks) provides most accurate dating
• Irregular cycles make LMP method less reliable
• Ovulation can vary by several days each cycle
• These are estimates - consult your healthcare provider
Frequently Asked Questions
How accurate is the conception date?
Conception date estimates are typically accurate within 3-5 days. Early ultrasound provides the most precise dating.
Can I determine paternity from conception date?
Conception dating alone cannot definitively determine paternity. DNA testing is required for accurate paternity determination.
What if my cycles are irregular?
For irregular cycles, ultrasound dating is more reliable than LMP-based calculations. Consult your healthcare provider.