Pregnancy Test Calculator

This tool is date arithmetic for working out when a home pregnancy test is worth taking. Enter the first day of your last period with your usual cycle length, or an ovulation date you already know, and it counts forward to the implantation window, the earliest date a sensitive test could show a positive, and the date a result is most reliable. It reads nothing but dates, so it cannot tell you whether you are pregnant and it is not a substitute for a test or a clinician. Ovulation shifts from cycle to cycle, and a test taken early can read negative while a pregnancy is under way.