Conception Calculator
Calculate your most fertile days, ovulation date, and estimated due date based on your menstrual cycle to optimize your chances of conception.
Cycle Information
Most women have cycles between 21-35 days. The average is 28 days.
The conception calculator estimates the likely date of conception based on the last menstrual period or a known due date. Conception typically occurs 11-21 days after the first day of the last period. This estimate helps understand the timing of pregnancy development.
How Conception Date Is Estimated
Ovulation occurs roughly 14 days after the first day of the last menstrual period in a 28-day cycle. Fertilization must happen within 24 hours of ovulation, though sperm can survive in the reproductive tract for up to 5 days. The conception window spans about 5-6 days each cycle, centered around ovulation.
Why Conception Dates Are Approximate
Cycle length varies from person to person and month to month. Ovulation does not always occur on day 14. The exact moment of fertilization cannot be observed. Because of these variables, a conception date estimated from the last period may be off by several days. Ultrasound measurements provide a more accurate gestational age.
Frequently Asked Questions
Can I know my exact conception date?⌄
Not with certainty. Conception dates are calculated estimates based on cycle timing. Only a small number of people know the exact date of intercourse that led to conception, and even then, fertilization may occur days later.
Does conception happen on the same day as intercourse?⌄
Not necessarily. Sperm can survive 3-5 days in the reproductive tract, so conception can occur days after intercourse. The calculator uses the day of ovulation as the estimated conception date.