After fertilisation the embryo travels down the fallopian tube for several days before burrowing into the uterine lining. Some people notice light spotting (implantation bleeding) at this time. A large study found most implantation happened 8–10 days after ovulation.
How to use the Implantation Calculator
- I know my…
- First day of your last period
- Average cycle length
- Ovulation date
Results update as you type, and every field accepts the units shown in its menu.
How it works
Enter your last period and cycle length, or your ovulation date if you tracked it.
Inputs explained
| Field | What to enter |
|---|---|
| I know my… | Choose one: Last period and cycle length, Ovulation date |
| First day of your last period | A date |
| Average cycle length | In days |
| Ovulation date | A date |
What each result means
- Earliest implantation = [Ovulation] + 6
- Most likely implantation = [Ovulation] + 9
- Latest implantation = [Ovulation] + 12
- Earliest positive pregnancy test = [Ovulation] + 10
Health note: this calculator is for education and screening only and is not a diagnosis or treatment advice. Discuss your results with a qualified clinician.
Formula
Ovulation ≈ LMP + cycle length − 14
Implantation = ovulation + 6 to 12 days (most often 8–10)
hCG detectable ≈ 2–3 days after implantation
Worked example
Inputs — I know my…: Last period and cycle length; First day of your last period: 2026-10-05; Average cycle length: 28 days.
Results — Ovulation = Mon, October 19, 2026; Earliest implantation = Sun, October 25, 2026; Most likely implantation = Wed, October 28, 2026; Latest implantation = Sat, October 31, 2026; Earliest positive pregnancy test = Thu, October 29, 2026.
Key terms
- Implantation
- Attachment of the embryo to the uterine lining.
Frequently asked questions
What does implantation bleeding look like?
Light pink or brown spotting lasting a day or two, lighter than a period.
Can I feel implantation?
Some people notice mild cramps, but most feel nothing.
When will a test be positive?
Usually 2–3 days after implantation, often around the day of the missed period.