Implantation Calculator

When Does Implantation Occur?

Implantation is when a developing embryo attaches to the uterine lining. In natural cycles, this usually happens 7 to 11 days after ovulation, most often around day 9 post-ovulation. Timing affects when hCG rises enough for home pregnancy tests to turn positive. Use this calculator from ovulation date, last menstrual period (LMP), or IVF transfer date. For broader pregnancy dating, see the Pregnancy Due Date Calculator and Pregnancy Weight Gain Calculator.

Natural Conception: Ovulation or LMP

If you know your ovulation date, implantation is estimated 7 to 11 days later, with day 9 as the most likely. If you only know LMP, ovulation is estimated as cycle length minus 14 days, then implantation is calculated from that ovulation estimate. A typical 28-day cycle implies ovulation around day 14 and implantation around cycle day 23.

IVF Embryo Transfer

After IVF, implantation timing depends on embryo stage. Day 3 cleavage embryos typically implant 4 to 7 days after transfer; day 5 blastocysts usually implant 2 to 5 days after transfer. The calculator shows a likely date, a window, and the earliest approximate date for a positive pregnancy test (about 3 days after likely implantation).