
Estimate your conception date based on due date, last period, or ultrasound
Conception Calculator
Understanding Conception Dates
Determining the exact date of conception can be challenging because there are many factors involved in the process. This calculator provides estimates based on the information you provide.
How Conception Works
Conception occurs when a sperm fertilizes an egg. This typically happens within 24 hours after ovulation. However, sperm can live inside the female reproductive tract for up to 5 days, which means intercourse that occurred several days before ovulation can result in pregnancy.
Calculation Methods
Due Date: Pregnancy typically lasts about 280 days (40 weeks) from the first day of your last menstrual period. Conception usually occurs about 14 days before your due date.
Last Menstrual Period: Ovulation typically occurs about 14 days before your next period would start. For a 28-day cycle, this would be around day 14.
Ultrasound: Early ultrasounds can measure the size of the embryo to estimate gestational age, which can then be used to calculate conception dates.