An implantation calculator estimates when a fertilized egg is likely to implant in the uterus — a key step in early pregnancy. By using your ovulation date or the first day of your last menstrual period (LMP), it helps you predict the earliest signs of pregnancy, such as spotting or cramping. Ideal for those trying to conceive, this tool gives insight into when implantation may occur and when to expect early pregnancy symptoms or test results.
Implantation is when a fertilized egg attaches to the uterine lining. It typically occurs 6 to 12 days after ovulation.
You enter either:
Your ovulation date (if known), or
The first day of your last period and average cycle length.
The tool then estimates your likely implantation window.
The embryo releases hCG (human chorionic gonadotropin), the hormone detected in pregnancy tests.
Some people may notice implantation spotting, mild cramping, or fatigue.
Implantation spotting is usually:
Light pink or brown
Short (a few hours to 1–2 days)
Occurs before your expected period
Knowing your implantation window can:
Help time your pregnancy tests more accurately
Reduce confusion between implantation spotting and your period
Offer emotional reassurance during the two-week wait
Use with an ovulation tracker or BBT charting
Combine with symptom tracking and luteal phase length
Note any mid-cycle bleeding or cramping
Staying cool and comfy
Choosing the right menstrual product
Baby development at 25 weeks
Finding joy in small things
Setting up the nursery
Preparing your body for birth
Managing heartburn naturally
Bathing daily during your period