Conception Calculator
Calculate when conception most likely occurred based on your last menstrual period or due date. Find your fertile window, ovulation date, and implantation timeline.
Conception Calculator
Calculate Conception Date
Enter your information and click calculate to find out when conception most likely occurred.
How to Use the Conception Calculator
- Choose Calculation Method: Select between Last Menstrual Period (LMP) or Due Date
- Enter LMP Information: Provide first day of last period and average cycle length
- Or Enter Due Date: Input your calculated or estimated due date
- Calculate: Click the button to see your conception date and fertility timeline
- Review Results: See conception date, fertile window, ovulation date, and implantation window
- Plan Accordingly: Use this information for pregnancy planning or understanding
Understanding Conception & Fertility
Key Fertility Dates
Conception Facts
Related Pregnancy Tools
Frequently Asked Questions
How accurate is the conception date calculation?
Conception date calculations are estimates based on average cycle lengths and ovulation timing. The actual conception date could vary by several days. Ultrasound dating is more precise for determining gestational age.
When does conception actually occur?
Conception typically occurs on or very close to ovulation day, usually around day 14 of a 28-day cycle. However, sperm can survive for up to 5 days, so intercourse before ovulation can still result in conception.
What is the fertile window?
The fertile window is the 6-day period during your menstrual cycle when pregnancy is possible. This includes the 5 days before ovulation (when sperm can survive) plus ovulation day itself.
Why is there a conception window instead of a single date?
There's a conception window because sperm can survive in the reproductive tract for several days, and the exact timing of ovulation can vary slightly. This gives a range of possible conception dates.
When does implantation occur?
Implantation typically occurs 6-12 days after conception. This is when the fertilized embryo attaches to the uterine wall and pregnancy hormones begin to be produced, which is what pregnancy tests detect.