Calculate your implantation window and when a pregnancy test may turn positive — based on your last period, ovulation date, or IVF transfer. No data is stored or transmitted.
About Implantation & Pregnancy Testing
What is implantation?
Implantation is when the fertilized egg (blastocyst) burrows into the lining of the uterus (endometrium). This normally happens 6 to 12 days after ovulation and fertilization, with most implantations occurring around day 8 to 10. Until implantation occurs, no pregnancy hormone (hCG) is produced, so no test can detect the pregnancy.
Why does the timing of implantation matter for testing?
A pregnancy test — blood or urine — can only turn positive after implantation because hCG is only released after the embryo connects with the mother's blood supply. Testing before implantation, or before hCG has risen enough to detect, will always give a negative result even if you are pregnant. This is the most common reason for a "false negative" early test.
Blood test vs. urine test: what is the difference?
A blood test (serum beta-hCG) can detect as little as 1–2 mIU/mL of hCG. A urine home pregnancy test (HPT) requires at least 20–25 mIU/mL to turn positive — meaning the blood test becomes positive 2–3 days earlier than a urine test. Neither test can detect pregnancy before implantation.
Important: These calculations are estimates based on average implantation timing. Individual biology varies. A negative test before your period is due does not rule out pregnancy. For the most accurate result, test on or after the first day of your missed period. All calculations are performed in your browser — no data is sent or stored.
Possible implantation signs (not diagnostic)
Light spotting (implantation bleeding)
Mild cramping or pelvic pressure
Nausea (less common this early)
Slight rise in basal body temperature
