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What does cM Shared Mean in DNA results?

What does cM shared mean in your DNA results? What does shared DNA mean? Learn the answers to these questions in this post, as well as where to find shared cM information on your DNA match list.

To begin the discussion, it is important that you understand two important definitions:

  • cM: an abbreviation for the word “centimorgan”
  • centimorgan: the genetic distance between two points on a chromosome

The word centimorgan is usually used to describe the length of a DNA segment. A genetic length, not physical length, however.

What does cM Shared Mean in DNA results_

Understanding the meaning of shared cMs or shared DNA can help you learn more about how you are related to your DNA matches. Generally speaking, the more cMs someone shares with us, the closer our genealogical relationship.

Towards the end of this post, I will describe more about how to use centimorgans (cMs) to estimate your relationship with your DNA matches.

What does shared cM mean?

Most of you probably arrived at this post because you saw “shared cM” on a DNA match profile, and you want to know what this means. You may even be curious about whether understanding this in more detail can help you guess how you and a match are connected.

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The “relationship” that all DNA testing companies give us are just estimates, and we can use outside information, like our family tree, combined with shared cMs to make an even better estimate!

If you haven’t yet started building a family tree, today is a perfect time to get started. It’s free to get started building your tree on Ancestry, which is the site I use.

A subscription is not required, but I have one and recommend it.

If you use the following sponsored link, you can get a two-week free trial on Ancestry – perfect for adding records and documents to your tree:  Ancestry Free Trial

As I mentioned above, cM stands for “centimorgan, and a centimorgan measures genetic distance, typically between two points on a chromosome. When two people have identical DNA between two points on a chromosome, we call this an identical DNA segment.

These two people with identical DNA might show up as DNA matches to each other, especially if the matching DNA segment is longer than about 6-7 cMs.

The “size” of identical DNA segments is usually described using the word centimorgans.

What does shared DNA mean?

Some people (and websites) describe the total amount of centimorgans shared between two people as “shared DNA”, which is very much is. When you see “shared DNA” on your DNA match list, understand that it means the same thing as shared centimorgans as defined above.

You might occasionally see “shared DNA” expressed as a percentage, especially on sites like 23ande. You can use the calculator on DNA Painter (click here) to enter in the percentage shared and see the approximate centimorgan equivalent.

Where to find Shared cM on Ancestry DNA?

On Ancestry DNA, shared cM information will show up directly on your DNA match list. You can access your DNA match list directly from any page on the Ancestry site via the “DNA” tab on the top of the page, or from your DNA results dashboard page.

On your DNA match list, you will see the estimated relationship in bold and in normal text below it will say “Shared DNA”. The number that you see is the total number of centimorgans across the specified number of DNA segments.

this image describes how to find shared cM information on Ancestry DNA
In this image from my Ancestry DNA results, you can see shared cM information right from my DNA match list. It says “Shared DNA” and then describes the total number of shared centimorgans along with total number of DNA segments

To learn more about understanding your Ancestry DNA results matches, check out this post:

Where to find shared cM on 23andMe

If your DNA match’s privacy settings allow, you can access the total number of shared cMs, as well as other DNA segment data, using the 23andMe chromosome browser.

The image below shows where to find the shared cM information on the 23andMe chromosome browser. Read “How to use the 23andMe Chromosome Browser” for more details.

How to find shared cM information on 23andMe
In the image above, I put a big red arrow pointing to the shared cM information between Bobbie and his DNA match. This information can be found on the chromosome browser (i.e. “DNA Comparison” tool)

For more about understanding your 23andMe results, you might find this post helpful:

Where to find Shared cM on Family Tree DNA?

Family Tree DNA displays shared cMs directly on the DNA match list. To see more detailed information about the location of the DNA segments, you must compare your DNA with that of your match in the chromosome browser.

The image below shows where the shared cM information is located on your Family Tree DNA match list:

where to find shared cM information on family tree dna
I highlighted the “Shared cM” column on Family Tree DNA from my own DNA results on Family Tree DNA

If you want to know more about your Family Tree DNA results, I wrote this post for you:

Where to find Shared cM on My Heritage

On your My Heritage DNA match list, you can see the shared cM information directly, as well as a lot of other information about your DNA match.

To the right of your DNA match’s name, you will see a column with some details about your connection with your match. Right next to where it says “Shared DNA”, you will see the total number of shared cMs as well as the percentage of DNA shared with your DNA.

The image below shows you exactly where you can see this information on your DNA match list (shown via the red arrow):

how to find shared cM information on my hertiage dna
The red arrow in the image above points to the shared cM information, which you can see directly from your DNA match list

To learn more about your My Heritage DNA results, read this post:

You can use shared centimorgans to determine your relationship to a match

The shared centimorgan information that you find on your DNA match list can help you learn more about your connection to your DNA matches. I recommend this post to those who are learning more about using shared DNA to determine relationships:

Conclusion

I hope that this post has helped you understand more about shared cMs, total cMs, and how to find this information on your DNA testing site. If you have any questions about something that you read here, please join us in the discussion below.

Thanks for stopping by today!

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Melissa Campbell-Espe

Saturday 12th of December 2020

if i have a first cousin match of 864cm over 28 segments, could this be my birthfathers, sisters child?

James Wesley Young

Saturday 25th of July 2020

If the cM is 784 in a test of two people , what is the relationship? Can a person take a relative sample and send it in to a test lab and get an accurate result?

Mercedes

Sunday 2nd of August 2020

Relatives who share 784 centimorgans can have several different relationships. The autosomal DNA test that was already done is the best way to determine exactly how you are related. I would suggest comparing family trees and the DNA matches' genetic relationships with other family members. You can also check out the calculator on the following link in order to get an idea of the relationship possibilities: https://dnapainter.com/tools/sharedcmv4 Best of luck to you, Mercedes

Lu

Monday 27th of April 2020

I found a match of a close relative we share 1,568.633 cMs. Could this person be my half brother. I have never met my biological father and wonder if we are siblings. Thanks, Lu

Jsck Day

Saturday 18th of April 2020

What is the likelihood that a shared DNA of 884cM across 42 segments could be a close relative of mine? Might this be a niece/nephew or 1st or 2nd cousin?

Mercedes

Tuesday 21st of April 2020

Hi Jack, There is more than a 97% chance that this person is a relatively close relative, including the chance that they are a niece or nephew. I would point you to the following calculator: https://dnapainter.com/tools/sharedcmv4 You can see probabilities and other possible relationship types. You will likely have to use other clues, such as their age relative to you, geographic place of birth, and genealogical information in order to determine exactly how they are related to you. I wish you the best of luck in figuring it out :) Thank you for your comment - Mercedes

Kim Garner

Wednesday 4th of March 2020

Trouble determining my 3rd GGF with DNA. Both candidates are related so it could be either one. Only way to figure it out is with DNA but I don't know how?

Kim

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