Implantation Calculator
Implantation is when a fertilised egg embeds in the lining of the uterus — the moment pregnancy hormones begin to rise. Enter your last period and cycle length to estimate when it may happen and when a test could turn positive.
Estimates based on a regular cycle, for general information only — not medical advice or a diagnosis. Timing varies between people.
How it works
After ovulation, a fertilised egg takes about 6 to 12 days to reach and implant in the uterus, most often around days 8 to 10. Only after implantation does hCG start to rise, which is why testing makes sense a few days later. We estimate ovulation as roughly 14 days before your next period.
How this is calculated
Implantation usually happens about 6–12 days after ovulation (most often 8–10), when the embryo attaches to the uterine lining. This is an estimate — the timing, and any light "implantation" spotting, vary a lot between people.
Sources: ACOG, Mayo Clinic
Last reviewed: 2026-06
Frequently asked questions
When does implantation happen? +
Usually 6–12 days after ovulation, with days 8–10 being most common. We show that window based on your estimated ovulation day.
Is implantation bleeding real? +
Some people notice light spotting around implantation, but many don’t — and spotting can have other causes. It isn’t a reliable sign of pregnancy on its own.
Can I feel implantation symptoms? +
So-called implantation symptoms overlap closely with normal premenstrual changes, so they can’t confirm or rule out pregnancy. A test after your expected window is far more dependable.
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