How this calculator works
Wilcox and colleagues detected implantation through first urinary hCG appearance 6 to 12 days after ovulation in pregnancies lasting at least six weeks, most often on days 8 to 10. These are population observations, not a prediction for one pregnancy. Cycle mode assumes ovulation 14 days before the next period. IVF mode applies the same illustrative post-fertilisation day range by subtracting embryo age from transfer; it is an extrapolation, not a validated IVF implantation model. Symptoms cannot confirm implantation. The result is an estimate for information only and is not medical advice.
Formula
Window = ovulation + 6 to 12 days; common observed interval = +8 to +10 days. Cycle ovulation estimate = LMP + cycle - 14. IVF reference date = transfer - embryo age.
Worked example
For ovulation January 15, 2026, the illustrative window is January 21 to 27, with the commonly observed interval January 23 to 25.
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Frequently asked questions
Can a symptom prove the implantation date?
No. Bleeding, cramping and temperature changes are not reliable date markers.
Does a negative test during this window exclude pregnancy?
No. Test timing and sensitivity matter; follow the test instructions and seek clinical advice when needed.
Is the IVF mode validated separately?
No. It maps the observational interval to embryo age for illustration and does not predict an individual transfer outcome.