Conception Date Calculator
Calculate when conception occurred based on due date, ultrasound, or current pregnancy stage
About this calculator
A conception date calculator helps determine when fertilization likely occurred based on your pregnancy timeline. By using your due date, ultrasound measurements, or current pregnancy stage, this tool estimates the approximate date of conception. This information is valuable for understanding your pregnancy timeline, tracking fetal development milestones, and providing context for prenatal appointments. The calculator uses standard pregnancy duration of 280 days from last menstrual period to provide accurate estimates.
How to use
Enter one of three data points: your estimated due date, ultrasound measurements with scan date, or current pregnancy stage (weeks/days). The calculator will work backwards from this information to estimate when conception occurred. Select your preferred input method and fill in the corresponding fields for the most accurate results.
Frequently asked questions
How accurate is the conception date estimate?
Conception date estimates are typically accurate within 1-2 weeks, as ovulation timing can vary between women and cycles.
Which method gives the most accurate conception date?
Early ultrasound measurements (6-12 weeks) typically provide the most accurate conception estimates compared to due dates or symptoms.
Can I use this calculator if I have irregular periods?
Yes, the calculator works regardless of cycle regularity since it calculates backwards from pregnancy milestones rather than menstrual dates.