Implantation date calculator
Implantation happens days after ovulation, and the pregnancy hormone only appears in urine after it, so this helps you time a test.
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Processing and privacy: The result is calculated inside your browser and your data is not sent to any server.
How to use it
- Enter first day of your last period and average cycle length.
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
Ovulation = last period + cycle length - 14. Implantation can occur 6 to 12 days after ovulation, most often 8 to 10 days (Wilcox 1999). Test day = expected period = last period + cycle length.
Example
Inputs: First day of your last period = 2026-09-01, Average cycle length = 28 days. Result: Most likely implantation: 2026-09-23 to 2026-09-25; Earliest possible: Monday, September 21, 2026 (2026-09-21); Latest possible: Sunday, September 27, 2026 (2026-09-27).
Limits and caveats
- It depends on the estimated ovulation day; if ovulation is late, implantation is too.
- Light implantation spotting does not happen to everyone and does not confirm pregnancy.
Questions about this tool
When does a home test show pregnancy?
The hormone starts rising after implantation, and a test is dependable from the day your period is due onward.
How is implantation bleeding different from a period?
It is usually very light, pink or brown, and lasts a day or two, while a period is heavier and longer.
Does an early negative test rule out pregnancy?
Not always. If your period does not come, test again in 2 to 3 days.