Implantation Window Estimator

When implantation happens and when spotting may occur. Free, private and instant.

How to use the Implantation Window

  1. Pick first day of your last period.
  2. Enter average cycle length (days).
  3. Choose luteal phase (ovulation to next period): 10 days, 11 days, 12 days, 13 days and more.
  4. Press Calculate to get an instant result with a colour scale, chart and plain-English explanation.

About the Implantation Window

After ovulation and fertilisation, the embryo implants in the uterus 6 to 12 days later, most often 8 to 10 days after ovulation. This tool shows your estimated implantation window, when light spotting may appear and when a pregnancy test is useful.

Also known as: implantation calculator, implantation date calculator, when does implantation happen, implantation bleeding date.

Worked example

Dates in this example are worked out as if today were 5 Nov 2026.

Implantation window: 11 Nov - 17 Nov (Today is about 0 days past ovulation). After ovulation on 5 Nov 2026, implantation usually happens 6 to 12 days later, most often 8 to 10 days (13 Nov - 15 Nov 2026). Implantation spotting, if it happens, appears in this window.

Formula and cut-offs

Implantation = ovulation + 6 to 12 days (peak 8-10 days). Implantation bleeding is light spotting that occurs in about 1 in 4 pregnancies.

Frequently asked questions

When does implantation happen?

Between 6 and 12 days after ovulation, most commonly 8 to 10 days.

What does implantation bleeding look like?

Light pink or brown spotting for a few hours to 2 days, lighter than a period.

When can I test after implantation?

hCG rises after implantation; most tests are reliable from the day your period is due.

Sources and references

Written and checked by the MediHub editorial team against the sources above. Read how we build and review our calculators.

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Last updated . This calculator is for education only and is not medical advice. See the medical disclaimer.