Conception Calculator
Calculate your most likely conception dates based on your menstrual cycle, and estimate your due date with our free online conception calculator.
Category: Fitness & Health
The average menstrual cycle is 28 days, but it can range from 21 to 35 days.
Conception Calculator
Enter your last period date and cycle length to estimate conception dates and your due date.
Frequently Asked Questions
How is the conception date calculated?
The conception date is estimated based on ovulation, which typically occurs about 14 days before the start of the next menstrual period. The fertile window includes the 5 days before ovulation and the day of ovulation itself. Conception most likely occurs within this window, as sperm can survive up to 5 days in the female reproductive tract, and the egg is viable for about 24 hours after ovulation.
How accurate is the conception date estimate?
Conception date estimates are approximations based on average cycle patterns. The accuracy depends on how regular your cycles are. Even with regular cycles, ovulation can vary by a few days from month to month due to stress, illness, travel, or other factors. The estimate provides a likely range rather than a precise date.
How is the due date calculated from conception?
The due date is typically calculated as 266 days (38 weeks) from conception, or 280 days (40 weeks) from the first day of the last menstrual period. However, only about 5% of babies are born exactly on their due date. Most babies are born within two weeks before or after the estimated due date.
Can I use this calculator if I have irregular periods?
This calculator works best for those with regular menstrual cycles. If you have irregular periods, the estimates will be less accurate since it's harder to predict when ovulation occurs. In cases of irregular cycles, tracking additional fertility signs like basal body temperature or using ovulation predictor kits can provide more accurate information.