How Is Pregnancy (Pregnancy) Calculated?

If you’re trying to have a baby – or if you really paid off, pay close attention to sex and have a better memory than we do, you may know that there are a lot of things that need to be in your body before you get it. big fat positive on pregnancy test. The process goes like this:

  1. Your body releases a mature egg. (This is ovulation.)
  2. Sperm – either already in your body (as little boys can survive up to 5 to 6 days in the uterus) or simply making their big entrance in the hours before ovulation travels to the Fallopian tubes to meet the egg.
  3. A sperm fertilizes an egg – it really only takes one! (This is an understanding.)
  4. The fertilized egg moves one of the Fallopian tubes towards the uterus.
  5. Fertilized egg nests or implants in the wall of the uterus (implantation.)

Some of these steps happen instantly, while others can take a day (ovulation) or even a week.

But implantation is especially key to having a positive pregnancy test, so it’s important to calculate when it might occur. That’s because implantation triggers your uterus to start producing the “pregnancy hormone” human chorionic gonadotropin (hCG).

Let’s take a look at how to calculate your implantation date.

If You Know Your Ovulation Date;

A mature egg has about 12 to 24 hours after it is released (ovulation) when it can be fertilized.

After fertilization, the journey of the egg down the Fallopian tubes can take anywhere from 6 to 12 days, but 9 days is average.

If you know your ovulation date, here’s how to calculate your implantation date:

Ovulation date + 9 days = Implantation date (give or take a few days)

If You Know the Date of the First Day of Your Due Date

Due Date Calculator|  Calculate EDD By Conception Date

If you know this, you can do the calculation in two ways. These methods are less accurate than knowing your ovulation date, but they can still predict implantation for you.

Method 1: Determine your ovulation date first

First, consider your average cycle length. Use this to calculate your approximate ovulation date:

Cycle length (number of days between periods) – 14 days = number of cycle days for ovulation

This calculation is used because the luteal phase (the time after ovulation) is usually around 14 days, even if your cycle is longer than 28 days.

For example, if you have a 30-day cycle, you probably ovulated around day 16 of the cycle. If you have a 34-day cycle, you probably ovulated around cycle day 20.

Add this number of days to the date of the first day of your last period. Use this ovulation equation, using the relevant date as your “known” ovulation date:

Ovulation date + 9 days = Implantation date (give or take a few days)

Example: Let’s say the first day of your last cycle (cycle day 1) is May 2nd. Your cycle length is usually 30 days. This means that you may have ovulated on May 16 or 17, 30 – 14 = cycle day. Your expected implantation date will be around May 17 + 9 days = May 26.

Another way to get your ovulation date is to use our ovulation calculator retroactively.

Method 2: Use standard averages

This method assumes you ovulated around day 14 of the cycle, and it takes about 9 days for the fertilized egg to reach the uterus. It is based on a 28-day cycle.

Date of first day of last period + 23 = Date of implantation (give or take a few days)

This method is not a very valid method because not all women ovulate on day 14 of their cycle.

When to Take a Home Pregnancy Test?

If implantation has occurred, your body will start producing hCG. However, it should develop a bit before you can detect it with a pregnancy test. So your best bet is to wait at least 3 to 4 days to test after implantation.

most accurate? Wait until the end of the time you missed. For most women, this will be pretty close to 5 to 6 days after implantation. Waiting even one more day without knowing it while trying to conceive can be absolutely unbearable.

Just know that if you test before enough time, you could get a negative result and still be pregnant. Give your hCG time to build up more and test again in a few days.


No implantation calculator will be exact because every body and every pregnancy is unique. But these calculations can help you predict when you might have implantation symptoms and when to take a pregnancy test.

Your estimated implantation date can help you figure out if you are having period bleeding or implantation bleeding.

If you have been working for more than a year (or more than 6 months if you are over 35), talk to your doctor. They can help diagnose problems that could prevent pregnancy and discuss your options for getting pregnant.

Healthline, Implantation Calculator: Figure Out When It’s Most Likely to Occur, 2019


  • Bradley D, et al. (2019). Time to conception and the menstrual cycle: an observational study of fertility app users who conceived. DOI:
  • Conception: How it works. (n.d.).
  • SuRW, et al. (2015). Implantation and establishment of pregnancy in human and nonhuman primates. DOI: 10.1007/978-3-319-15856-3_10
  • Trying to conceive.(2018).

Hi, I'm Alex Huynh, an expert in the field of mesothelioma. I have worked in this field for more than 10 years. With my experience and knowledge in this field, I decided to set up a website mesothelioma media to help people treat mesothelioma.

We will be happy to hear your thoughts

Leave a reply

Mesothelioma Media