Implantation Calculator
Estimate your implantation window and date from ovulation or your last period.
Enter the first day of your most recent period.
The average length of your menstrual cycle.
Most Likely Implantation Date
Implantation Window
Estimated Ovulation Date
How the Implantation Calculator Works
Implantation is the moment a fertilised egg (blastocyst) attaches to the lining of the uterus, marking the true start of pregnancy. It usually happens between 6 and 12 days after ovulation, with day 9 being the most common. This calculator estimates ovulation from the first day of your last menstrual period and your average cycle length, then derives the implantation window and the single most likely implantation day.
Ovulation Date = LMP + (Cycle Length − 14) days
Implantation Window = Ovulation + 6 days … Ovulation + 12 days
Most Likely Implantation = Ovulation + 9 days
Frequently Asked Questions
What is implantation?
Implantation is when the fertilised egg embeds itself into the uterine lining, typically 6 to 12 days after ovulation. It is the point at which the body begins producing the pregnancy hormone hCG.
How accurate is this estimate?
The result is an estimate based on average cycle data and a standard 14-day luteal phase. Actual ovulation and implantation timing vary between individuals and cycles, so treat the window as a guide rather than an exact date.
Why does cycle length matter?
Ovulation usually occurs about 14 days before your next period. A longer or shorter cycle shifts ovulation, and therefore the implantation window, earlier or later accordingly.
Medical disclaimer: This calculator provides an estimated implantation window based on standard cycle averages and should not replace professional medical advice. Ovulation and implantation timing vary, and individual results may differ. Always consult your doctor or midwife for personalised guidance.