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Implantation Calculator

Created by Łucja Zaborowska, MD, PhD candidate
Reviewed by Dominik Czernia, PhD, Jack Bowater and Aleksandra Zając, MD
Last updated: Jan 18, 2024

Our simple implantation calculator allows you to discover your implantation date. Don't worry if you don't know your ovulation date yet - we've got you covered. We'll help you answer "When did the implantation occur?", no matter if you're trying to conceive naturally or with the help of fertility treatment.

Our DPO calculator has even more to offer; in the paragraphs below, we will cover the essential issues regarding implantation, ovulation, and fertility as a whole.

We try our best to make our Omni Calculators as precise and reliable as possible. However, this tool can never replace a professional doctor's assessment. If any health condition bothers you, consult a physician.

How many days past ovulation does implantation occur?

The answer is simple: implantation usually happens after 9 days after ovulation. Remember, nature tends to break any rules you put on it - implantation time may be as short as 7 days, or as long as 11 days, depending on the person. You can expect a positive pregnancy test a few days afterwards, as your body's hCG levels need time to rise to a detectable level!

Implantation date = Ovulation date + 9 days

We now know the implantation rules (as loose as they may be), but we still need to obtain an answer to the question "How many days past ovulation am I?" We will have to make some additional calculations - that's why we decided to create this combined ovulation and implantation calculator. Remember, the task might be quite challenging if your periods are irregular!

  • LMP - the first day of your Last Menstrual Period; and
  • Menstrual cycle length - is estimated to be 28-days long for the average woman.

Ovulation date = LMP + (length of your menstrual cycle - 14 days)

Why 14 days? Ovulation happens between two phases of the menstrual cycle. The length of the menstrual period depends on the length of the first phase, while the second phase lasts 14 days, and is relatively identical among all the women. Discover your menstrual cycle's details in the section below.

Now that you've put the Implantation calculator into use and gained some new information... why don't you discover even more? Check:

Implantation bleeding calculator

We already calculated your implantation time, which is when the implantation bleeding may happen. During implantation, the uterine lining is very thick, and filled with many twisted blood vessels. The implanting embryo has to somehow "eat" its way into it, and a little bleeding may happen as a result.

What other tools can we use as an implantation tracker?
We may use many different methods to define our ovulation date, which allows us to find the implantation date accurately. It's a good way to go, especially if your periods are irregular!

These methods are:

  • Basal temperature - Your body temperature decreases before ovulation and increases 24 hours after. You need to check your temperature every day before getting out of bed and keep a record of all readings. Charts work best. 📈
  • Ovulation tests - You can use them just like pregnancy tests.
  • Pain caused by ovulation - some women experience some unpleasant sensations a few days before and after ovulation.
  • Cervical mucus inspection - the cervical mucus changes its consistency during ovulation. It gains the texture of an egg-white - its purpose is to facilitate the travel of sperm through the uterus.
  • Ultrasound examination - A method available later on during the pregnancy, helps you discover your ultrasound Expected Date of Delivery, and compare it to the date established using the date of your last menstrual period.

Implantation calculator IVF

This implantation date calculator is a little bit different when it comes to fertility treatment, as, at the moment of the IVF transfer, the embryo has already started its development. It's put directly into its final destination - the uterus. This single factor eliminates the long route of the embryo from the fallopian tubes (the place of fertilization) to the thickened lining of the womb.

Attachment may start as early as two days after the transfer, and as late as seven days afterward. The speed of the process also depends on how developed the transferred embryo is - whether it's in the cleavage stage (2-3 days old) or in the blastocyst stage (4-6 days old). In general, the older the embryo, the quicker the process.

This IVF due date calculator might come as handy!

Menstrual cycle

A Days Past Ovulation (DPO) calculation in pregnancy is based on basic knowledge of the female's menstrual cycle. The menstrual cycle is divided into two phases: follicular and luteal. Ovulation is a short, 24 hour period between them. DPO calculations in pregnancy are based on following theory:

when does the implantation occur during menstrual cycle
  1. We mark the beginning of the menstrual cycle by the first day of menstrual bleeding. Bleeding happens because the lining of the uterus thickens and collects resources every month, preparing for a possible pregnancy. If the pregnancy doesn't happen, it must shed excessive tissue.

  2. The follicular, proliferative phase is called the "relative infertility" period, since women can still get pregnant if intercourse happens right before ovulation. We can calculate the possible date of ovulation, but we cannot be entirely sure when it will happen - many factors may influence it, for example, stress or severe infection. The follicular phase is responsible for differences in the length of the menstrual cycle between different women.

  3. Ovulation time! Check your ovulation day with the ovulation calculator, which can be used as a quick fertility test.

  4. The luteal, secretory phase is called the "post-ovulation infertility period". We already know that ovulation has happened, and the woman cannot get pregnant until the end of the month. This phase is relatively identical among all women, and lasts 14 days. During this period, the uterus is preparing to accept the embryo that should already be traveling through the fallopian tubes.

What factors might influence the menstrual cycle and the resultant pregnancy?

  • Stress;
  • Infections;
  • Excessive or insufficient weight before conception and weight gain during the pregnancy;
  • Hormonal diseases, such as Policystic Ovary Syndrome (PCOS);
  • Congenital disorders, such as the Turner syndrome; and
  • Other severe comorbidities.


When does implantation occur?

Implantation usually occurs 9 days after ovulation. This number does however differ from woman to woman, it can be anywhere from 7 days to 11 days. You’ll still have to wait a few days after implantation to be sure to get a positive pregnancy test though!

How long does implantation bleeding last?

Implantation bleeding can last anywhere from a few hours to a few days, depending on the woman, and is a common symptom of pregnancy. However, if the bleeding is excessively heavy, or occurs for more than two days, consult your doctor.

Can you take a pregnancy test during implantation bleeding?

While taking a pregnancy test during implantation bleeding is safe, though it is unlikely to give you an accurate result. This is because your levels of the hormone that a pregnancy test detects, hCG, have not reached sufficient levels. You should take it when your next period is due.

How long does implantation take?

From ovulation, implantation takes anywhere between 3 and 12 days, depending on a conception method. The actual process of implantation takes only a few hours, and may be accompanied by some bleeding.

What does implantation bleeding look like?

Implantation bleeding is different to a regular period - it has a thinner consistency, and is lighter in color, usually being pink or brown. It usually is just a few spots, but could be slightly heavier. It shouldn’t be of a similar quantity to your normal period, however. If your bleeding is excessive, or lasts for more than two days, consult your doctor.

Łucja Zaborowska, MD, PhD candidate
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