Pregnancy Test Calculator
Timing is key for accurate pregnancy test results. This calculator estimates when to take a pregnancy test based on your last period date, cycle length, and estimated ovulation day, so you can get the most reliable result possible.
Home pregnancy tests detect human chorionic gonadotropin (hCG), a hormone produced after a fertilized egg implants in the uterine lining. Implantation typically occurs 6–12 days after ovulation, and hCG levels rise rapidly afterward, doubling approximately every 48–72 hours in early pregnancy. Most home pregnancy tests can detect hCG levels of 20–25 mIU/mL, which is usually reached around 10–14 days after ovulation.
Testing too early is the most common cause of false negative results. The most reliable time to test is one day after your expected period (the first day of a missed period or later). Early-result pregnancy tests claim detection up to 6 days before a missed period, but accuracy at that point is only about 50–75%. By the day of the expected period, accuracy rises above 99% for most brands.
This calculator provides estimates based on average cycle characteristics. Individual variation in ovulation timing and implantation can affect when hCG becomes detectable. If you get a negative result but your period does not arrive, retest in 2–3 days or consult your healthcare provider.