Understanding your calculation
Method, example and limitations
How the calculation works
Conception estimates work backward from an estimated due date or use the entered cycle information. A window is more appropriate than assuming one certain day.
Example to check
A conventional due date is about 266 days after estimated conception, or about 280 days after the last menstrual period in a simplified 28-day cycle.
Before using the result
The actual day can differ because cycle length, ovulation and clinical dating vary. The output cannot establish paternity or confirm pregnancy.