Pregnancy Test Calculator
Home pregnancy tests detect hCG, a hormone that only starts rising after implantation — which itself happens 6–12 days after ovulation. Test too early and even a fertilised cycle reads negative. Enter your ovulation date (or work it out from your last period) to see your testing timeline.
Your timeline, day by day
Accuracy column reflects the typical claims and behaviour of home urine tests: sensitivity varies by brand and by how diluted the sample is (first-morning urine is the most concentrated). A negative result before your missed period does not rule out pregnancy — retest in two days if your period still has not arrived.
Why the wait is biological, not just conservative advice
After fertilisation, the embryo travels to the uterus and implants — on average around 9 days after ovulation, with a normal range of about 6–12 days. Only after implantation does hCG enter the bloodstream and then the urine, roughly doubling every two days at first. A test taken at 8 days past ovulation (DPO) is therefore racing a hormone that may not be detectable yet even when conception happened. That is why the same test, in the same cycle, can be negative at 10 DPO and clearly positive at 13 DPO.
Practical tips that actually move the odds
Use first-morning urine, when hCG is most concentrated. Check the test's stated sensitivity (measured in mIU/mL — lower numbers detect earlier) rather than its marketing name. Read the result inside the time window printed on the instructions, not later: evaporation lines on an old test are a classic false alarm. And if you get a negative but no period, wait 48 hours and test again rather than testing daily — hCG needs that time to roughly double.
If you think you might be pregnant, DueDateCalc can estimate your due date from your last period once you have a positive test.