Why the Big Y Test?

My recent article about the Big Y test sale and coupons bundled with a free 111 marker upgrade at Family Tree DNA generated quite a number of questions about the Big Y DNA test itself, and why a male might want to take one. I’ll answer that question, along with a few more that have arisen, but the coupon sale I referenced only pertained to December 2017. The rest of this article is still very relevant!

Why the Big Y?

Y DNA tests test a man’s direct paternal (usually surname) line and fall into two groups.

  • STRs – Short Tandem Repeats
  • SNPs – Single Nucleotide Polymorphisms

The first group, STRs, are the typical 12, 25, 37, 67 and 111 Y DNA tests.  STR marker location values change rapidly, as compared to SNPs which mutates more slowly.

Each STR test tests the number of STR markers it’s named for. In other words, a 37 marker test tests 37 marker locations with the goal of matching other men with the same surname. Often, as you test higher levels, the results become much more specific and you “lose” matches to men with non-matching surnames. In this case, “losing” is a good thing, like weight!

The closer the STR match on more markers, the more reliable the results. Fewer matches generally mean we’re filtering out the more distant matches in time and the closer in time you shared a common ancestor with the people you match the most closely on the highest marker test you’ve both taken.

In other words, you might match 50 people at 37 markers, but only 20 at 67 markers and 4 at 111 markers.  Those 4 men are the most closely related to you on that direct paternal line – which is why we strongly suggest that people upgrade to 111 markers.

You can see in this example from the Estes project that the first two people whose surname is Estes are not biologically descended from the same male as the last four individuals – because their STR markers showing in the project are quite different.

Because STR markers mutate more rapidly, they are very useful for genealogy – and are used for that purpose.  An exact high marker match (typically 37, 67 or 111) to a male with the same surname indicates that you share a common ancestor with that man, probably within the past few generations and certainly since the advent of surnames. STR mutations sometimes happen independently in different lines, and when that happens, it’s called matching by convergence.

SNPs, on the other hand, are much more stable and mutate at a much slower rate and are therefore sometimes not as useful for traditional genealogy – BUT – they have the power to look further back in time where we have no tools other than DNA to make discoveries about our ancestors.

In general, but not always, men known to descend from a common ancestor will share the exact same “terminal SNP” – meaning the SNP mutation that happened the most recently.  Sometimes a SNP mutation will have happened in the past few generations and men who share a common ancestor since the advent of surnames will have a different terminal SNP, but not often and if they do, it’s generally only one step down the haplotree from each other. Just the “son” leaf on that branch.

On the Big Y haplotree, above, of an Estes male, five people match him on the BY490 branch, six on the BY482 branch above, and so forth. Of course, the next question is who matches him on these branches, so he will look at his Big Y match list to see those individuals.

What this means is that, in general, SNPs define more distant clan relationships, because they happen less often, and STRs define more recent surname relationships – although the more SNPs that are discovered – the more instances of some overlap we see.

The following chart shows where the two kinds of testing are the most useful – which illustrates why we need both kinds of testing.

Sometimes, there are no new SNP mutations that have occurred in a particular since the adoption of surnames. Of course, there is an exception to every guideline, and it just might be you. In fact, it could be between you and your father, or your father and his father. You don’t know what you don’t know and the only avenue to discovery is DNA testing.

What Does the Big Y Do?

While the STR panel tests specific addresses on the Y DNA to read a specific location – the Big Y test is a scan that scans the majority of the Y chromosome.

In other words, the 37 marker test provides you with results for 37 individual locations, or alleles, on the Y chromosome by measuring the number of repeats found at those locations specifically.

However, the more DNA addresses to be checked, the more expensive the test – which is why STR testing is broken into panels.

The Big Y test scans the majority of the Y chromosome to compare to a standard Y DNA pattern.  Because scan technology, known as NGS or next generation sequencing, allows us to look at tens of thousands of locations, it is not as accurate as looking at one specific location (think google satellite view versus driving down the street).  The DNA sequencing equipment scans the entire Y chromosome several times, like 25 or 30, and then reports on how many times something out of the ordinary is seen at a specific location.

If the scan spots something unusual 10 times or more, it’s called as a positive “result.”  Ten times or less, it’s considered a blip and not a high enough confidence result to consider as a valid result to report to a customer.

Why Do You Care?

As a customer, you may not care about the scans and underlying scientific processes that I just described – but you do care about the outcome which is your confirmed haplogroup closest in time to you on the tree. That information is important genealogically.

The Y DNA haplotree is the result of mutations that occurred every few hundred or few thousand years over the lifetime of mankind.  The mutation that identifies you the most closely with your closest male relatives is the last mutation that occurred that you all share – or don’t – which means a new mutation happened since the advent of your surname, assuming you do actually descend from a common ancestor and don’t just circumstantially carry the same surname. Yes, that does occasionally happen.

The result for the customer who takes the Big Y test is that the haplogroup predicted through STR testing is confirmed and generally several more branches and leaves are added to your own personal haplogroup tree.

Family Tree DNA very accurately predicts your branch haplogroup when you take an STR test, but it’s a major branch, near the tree, not a small branch and certainly not a leaf.  Smaller branches can’t be accurately predicted nor larger branches confirmed without SNP testing. The most effective way to SNP test for already discovered haplogroups – plus new ones never before found – perhaps unique to your line – is to take the Big Y.

While all of this science may not sound exciting at first glance, the results certainly can be, for a genealogist anyway.

The Big Y:

  • Confirms estimated haplogroups.
  • Provides you with your haplogroup closest in time – meaning puts twigs and leaves on your branches.
  • Helps to build the Y DNA tree, meaning you can contribute to science while learning about your own ancestors.
  • Confirms that men who do match on the same STR markers really ARE in the same haplogroup.
  • Shows matches further back in time than STRs can show.
  • Maps the migration of the person’s Y line ancestors.

Together, STR and SNP tests provide us with the closest mutations meaning the most genealogically relevant as well as (generally) older and more distant mutations, giving us at least some information before the age of surnames. This means you will match men who adopted surnames about the same time your ancestors did.  If you are a McDonald, you might match men whose surname is Campbell, as an example. Or, you might match men with Scandinavian surnames.  All of these pieces of information add to the story of your ancestors before surnames and records – the point at which your paternal line is unquestionably lost to traditional genealogy. Big Y testing is a way to reach back behind that veil.

How else will you ever learn the history of your ancestor in that timeframe? And why wouldn’t you want to?


If you are interested in discovering any of this information, the Big Y is the most thorough avenue for the genealogist.  You can purchase some SNP markers individually, but that gets expensive very quickly, and you can’t learn about any new markers your DNA might hold if you purchase only SNP markers previously known to exist. Y DNA holds hundreds or even thousands of SNPs with mutations to report.

Additionally, many men’s DNA also holds never-before-discovered SNP mutations.  You can’t discover those any way other than a Big Y test.

Who Should Purchase the Big Y?

  • Males who want to discover their ancestor’s story before the advent of surnames.
  • Men who want to confirm and extend their haplogroup.
  • Men who want to be pioneers and discover new SNPs in their DNA – never previously found.
  • Males who want to participate in research and building the Y DNA tree.
  • Males who have previously taken some level of STR tests at Family Tree DNA.

The Big Y is only an upgrade test. You can only see the Big Y as a purchase option on your account as an upgrade.  Click on the blue Upgrade button located in your Y DNA section or at the top right of your personal page.


  • I want to discover my father’s paternal line, but I’m a female. What can I do?

Answer – Test your father or brother, or a male relative who carries your father’s surname and descends from the common male ancestor through the direct paternal line.  The article, Concepts – Who To Test For Your Father’s DNA will help you find a male to test for your father’s line.

  • I’m a male, but I haven’t taken any Y DNA test? How can I take the Big Y?

Answer – Easy.  Just order the BIG Y-500 which includes the 111 marker test, the Big Y and additional free STR markers.

  • I’ve already taken the 111 marker test? How do I order the Big Y?

Answer – Just click on your blue Upgrade button.



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58 thoughts on “Why the Big Y Test?

  1. If my dad has no matches at zero distance on his 67 marker test, is there still any genealogical value for him in running the big Y?

      • Thanks for the great answers. The challenge is to convince those two men to invest in the Big Y test (my first cousin [Jewish] and my father-in-law [non-Jewish and with the Smith surname]). Any chance the cost will decrease eventually? Both men took the 37 marker test.

  2. Thank you Roberta for your informative, honest, and accurate insights on the BIG Y test. For those of us with limited resources, being an educated consumer is the best way to maximize the benefits of various DNA test purchases.

    The holidays are rapidly approaching. Is everyone prepared to interview the oldest members of your families? (don’t forget to document or record conversations) Also, have you purchased an atDNA test kit for a gift, or to have on hand if a testing opportunity avails itself? Let a cheek swab or vial of saliva become a treasured family DNA heirloom.

  3. Is there any value to upgrading to the Big Y test if you (the male) has just a few matches at the 37-marker level?

    • Yes, you’ll be able to see matches of a different type. For example the Big Y matches often show groups of men before the ancestral surnames which gives you another hint as to where the paternal line came from.

  4. A terrific article, Roberta. Thanks.

    There’s some great work being done on connecting the tribes of the distant past to a genealogical time frame using Y DNA, and I hope people realize that a lot of it is being done by ‘citizen scientists’ like us. We need more people to test – especially if they’re R1b : )

  5. Roberta,
    Thank you so much for this post, which has been the most easily understood article on the Big Y vs basic Y tests that I’ve read … but I do have questions.

    I had my dad and a gentleman from a related line test at 111 markers. They matched with a genetic distance of 2. Then I had a backbone SNP test done on both. My dad’s came back R-Z295 and the other gentleman R-Z195 (3 steps above my dad’s). Through my research, I have theorized, but can’t document, that these 2 men had a common ancestor 4-5 generations back, in the early 1800s.

    What do their different SNPs tell me?
    Does the backbone SNP test determine the terminal SNP that the Big Y finds?
    No one in our surname project has done the Big Y. Would it be useful for me to upgrade my dad’s test to have that done?


  6. I have not taken the Big Y. Instead, I have paid for SNP packs that continue to define my Haplogroup and SNP. My Y-DNA Haplogroup (now) is R-A2425 which takes my ancestry to Northern Ireland. Why are you and others encouraging the Big Y when other cheaper tests accomplish the same thing?

    • SNP packs can only test kniwn SNPs. They can’t find never before reported SNPs on your Y chromosome. Only the Big Y can do that. Also, in some haplogroup it takes multiple SNP packs to get to the twigs in the tree. Without the Big Y, you don’t know whether you’re at the actual end of your line or not.

  7. I would love to do the big Y, I have already done the Nat Geographic test second edition and a further test at FDNA which confirmed I belonged to Z284, which is very interesting seeing I am from the UK and have traced my ancestors back to the 1700’s. I really would like to find some common ancestors before the beginning of surnames and it looks like the only way to do that will be the bigY. Will have to start saving. Great blog by the way, love it

  8. I have taken ever test that FTDNA offers which means that I have data and knowledge overload but my understanding would fit into a thimble. I have googled all those big words that I can neithger pronounce or spell but this explanation brings it to the front. Thanks for these words.

  9. There is no way of me getting a “Y” test on a male in my family. Please take me off this mailing list. Thanks


  10. Hi Roberta, thank you so much for your informative post! As I was reading though I couldn’t help but wish for a post such as this that incorporates the nuances and difficulties of yDNA testing men who are descended from former slaves. I get that the yDNA test is also very geared toward matching to men with common surnames. But this will usually not be the case for men who descend from a paternal line whose patriarch was enslaved.

    I also feel that the lack of posts directing Black Americans on what they can and can’t find through yDNA testing means that many of the men and families investing in atDNA testing will not invest in yDNA testing also.

    I have several examples of lines that I’m researching that have shown promising results with yDNA testing:

    1st example:
    My great great grandfather, John McClellan was born into slavery and served in the U.S.C.T., from his pension file we know that his father was another slave named Ben Anderson. Myself and an atDNA cousin match who had a brick wall ancestor named Bennie Anderson (too young to be Ben Anderson, but of an age to be a 1/2 brother to John McClellan) have spent years researching our connection. We’ve done segment triangulation analysis between her, myself, and others in both of our known McClellan and Anderson branches. We all triangulate on shared segments of dna with several Caucasian descendants of a Burrus/Dickerson couple. Some of our McClellan or Anderson descendants share as much as 73 cMs or 55 cMs of DNA with these descendants. yDNA testing was then done on John McClellan’s male line descendant: Ellis McClellan and Bennie’s direct male line descendant (despite the different surname) Corwin Greene. Corwin & Ellis match on 36 of 37 markers under the R-M269 haplogroup.

    Ellis has:
    4 Burrus matches that are 2 markers different
    4 Burrus matches that is 1 marker different
    1 Burrus match that is 0 markers different
    1 Gleave match this is 0 markers different

    Corwin has:
    4 Burrus matches that are 2 markers different
    1 Burrus match that is 1 marker different
    1 Gleave match this is 1 marker different

    2nd example:
    2 male line descendants of Abraham Paden (formerly enslaved and born in South Carolina) have tested. Both of them come back under the R-M269 haplogroup. With some Parrish surnames among their matches. We’re currently upgrading one of them to the 111 marker test now and expanding the atDNA testing to search for Parrish descendants among those cousin matches.

    3rd example:
    My 2nd great grandfather Tarlton Morrison was born enslaved and emancipated likely following the civil war. Based on 1870 and 1880 census records we determined that he and his wife’s oldest children were born in AL and their youngest 3 were born in MS, likely where they were living from 1870’s on. One of the oldest sons (my great grandfather Daniel) and the youngest son Marshall both have male line descendants who tested and match on 36 of 37 markers. Both are under the E-M2 haplogroup and both have no other matches aside from themselves. A middle son, George Morrison was the only one listed as mulatto and was listed as a step son to Tarlton. His male line has been yDNA tested. He comes back to a G-M201 haplogroup with the top three matches being 2 markers different and coming back to the Culbreath/Galbraith surname. There are several atDNA descendants who match George’s descendants who descend from a Thomas Dent Galbreath who died during the civil war. Thomas Dent Galbreath’s father in law (John Rowsom) owned slaves and all resided in Marion County, Alabama (my 2nd great grandmother’s (wife of Tarlton Morrison) maiden name is listed as Rousom on her youngest son’s documents. In researching John Rowsom, Thomas Dent Galbraith, and others in the county… I discovered Archibald Morrison living in Marion County, Alabama at the same time. He owned one slave who fit the age of Tarlton Morrison. John Rowsom owned slaves who fit the ages of Barbara and children. Also, Archibald Morrison was living in Tishomingo County, MS in 1870 and 1880 where Tarlton Morrison and his family were also located. One of the atDNA cousin matches to George Morrison’s granddaughter is in the 3rd to 4th cousin range.

    I think all of this is more than just coincidence. I also strongly believe that the yDNA testing can be very valuable for those who descend from former slaves.

    • Browsing this reply by Samantha Jones, the haplotype R-M269 and name “Parrish” caught my eye. A Campey relative of mine, who has tested at Y-67 and assigned R-M269, has no close matches, the closest being at a genetic distance of 6, Lawaha Parrish. There are four other Parrishes at a genetic distance of 7. That is 5/15 of his total matches at 67-marker level.
      Our Campey ancestors come from Yorkshire (places like Appleton Roebuck, Bolton Percy and Tadcaster) but their origin is a matter of speculation, with Italy and France both mentioned.
      I’d be interested to know whether you have come across the surname “Campey”, “Campi”, “Camplejohn” or similar in your research.

  11. Roberta – I love your work, so very clear and practical. In this case however I must take a slight exception. SNPs. These markers are not just ‘ancient’ anymore, in fact we have identified many SNP haplogroups dated to the beginning of surnames. Moreover, there are many cases of SNPs definitively marking surname lines into the recent genealogical time period (within the last 150 years). By contrast STRs (even at 111 markers) continues to be a ‘house of mirrors’ when trying to sort between different, distinct surname lines since the beginning of surname use. Please take a moment to consider the advances of SNP within the last two years among surname projects in your future research on the subject. Thanks.

    • I agree with you, which is why I said what I did. On the other hand, I don’t want to misset expectations and have people thinking that they are going to receive further differentiation and then not receive it. So it’s possible but not probable:)

  12. Your explanations are so much easier to understand than most of the literature available. Have you given any thought to hosting a seminar on genetic genealogy?

    • Bless you, thank you, and no:) Seriously, I’ve done conference planning in the past and it wasn’t fun. But thank you. I am doing some videos with various entities and will be publicizing those.

  13. The sale thing is somewhat confusing and may be aggravating if I understand it correctly.

    Two or three years ago I purchased the Y-111 test. May have gotten it on sale.

    Now if I want to upgrade to the Big Y test it’s going to cost $475.00 on sale.

    However there is a Big Y Bundle which includes the Y-111 test for $450.00.

    If my understanding of this is correct …. I feel I’m being financially punished for having purchased my test earlier.

    Cliff Crenshaw

    • The $450 is with the coupon, which you can apply to the Big Y too. It’s like anything else. If you purchased your car last year and it’s cheaper when the model years ends – you’re not being punished for purchasing earlier. It’s just the way the marketplace works. You can either purchase the Big Y now with the great discount and the coupon, wait and purchase it later and not have the info, and the price might go back up and not come back to this level again – because even the $475 (before the coupon) is at least $100 off, or you can wait and hope for better.

  14. This morning FTDNA sent me a coupon code for $50 discount for BigY upgrade. I just used the coupon code myself for my husband’s upgrade to BigY, but your readers may find a similar offer in their own inbox.

  15. For those who haven’t yet done any DNA testing, starting with the 12-marker test would be a cheaper alternative than the 37-marker test. The 12-marker test can still be ordered for new kits ordered via a group project for just $59. That brings the cost of the entire Y-DNA testing package down to just $509 (assuming a $25 coupon for Big Y).

  16. I can’t use my promo code, so maybe someone else can: $40 off mtFull Sequence R24LGNPV5SI8
    Please leave reply if using, as it is only to be used once.

  17. Roberta, I have people I am encouraging to purchase a Y DNA test who have no computer. Yeah they are out there! But they are also older and need a less techie discussion and I have done a little of this as president of Clan Bell. I need something with prices from you and or FTDNA/Ancestry that I can mail to a new DNA candidate that is straight forward and easily read. Got anything? I am surely NOT the only one! Our Bell DNA project administrators and I need to be able to put a physical check in the mail for them to get their kit; getting them their results with some meaning will be up to us though a letter with the report could be sent out by the testing company but most are simply not setup to handle such as the work is all “hands on.” Please let me hear from you. David Erwin Bell 1513 Anterra Drive Wake Forest, NC 27587 PS We plan to put your article “Why the Big Y?” on our [ http://www.clanbell.org ]( http://www.clanbell.org ) web page in the DNA section.

    • I think that the projects group at FTDNA may have something like that. I know they have flyers. As for the results, that’s another matter because the meaning of the results changes based on the results themselves.

  18. Hi, I have done 67 marker and BigY and also sent results to Yfull. BigY initially gave me 3 matches which have since disappeared when they upgraded from Hg19 to Hg38. Yfull have given me 6 matches ( same 3 from ftdna plus another 3) . My question is what is Hg38 upgrade for BigY and will I get my matches back on ftdna?
    Note: I match with 3 walloon/east french/Hesse people of which we have 1 SNP out, I have it tested as negative, they as positive, but the negative is 500 years older in age…….can this be correct?

  19. Since 2003 I have purchased each new test as it came out, 37, 67, up to the 111 with no coupons or sales. Now I feel like I wasted my money if free 111s are being given. I will wait a few years more and see where the Big Y prices head, or another company starts to offer the same. Thanks for your posts.

    Larry Liles Marshall, VA

    On Fri, Nov 17, 2017 at 7:54 AM, DNAeXplained – Genetic Genealogy wrote:

    > Roberta Estes posted: ” My recent article about the Big Y test sale and > coupons bundled with a free 111 marker upgrade at Family Tree DNA generated > quite a number of questions about the Big Y DNA test itself, and why a male > might want to take one. I’ll answer that question, ” >

    • The power of these tests is in matching, so if you do test elsewhere, your results won’t be in the data base to help you.

      DNA tests are just like everything else, you can wait forever to test waiting on a “better sale” and you will never test, or buy a car, or anything else.

  20. Am i need to tested my Y DNA CTS5492 again after i received my Y111 and the Big Y results? From my Geno 2.0, my Y DNA belong to Haplogroup O-CTS5492. My Big Y result confirm when i belonged to Haplogroup O-M133 – CTS11856 – F526 if i remember corretly. My CTS5492 test is available on my FTDNA Haplotree. It cost around $39.

  21. My brother tested 40 percent on the native American test I tested 8 percent my name is Holley did they think I was female would this explain the difference

  22. FTDNA gives estimates of a time frame for markers, e.g. 37, 67 & 111, based on generational (0, 1, 2, 3, etc.). However, they specifically say same surname which would imply a similar or near enough geographical location. Or a wide migration of family, e.g. war, famine, etc.

    Chart example > https://www.familytreedna.com/learn/y-dna-testing/y-str/two-men-share-surname-genetic-distance-111-y-chromosome-str-markers-interpreted/

    My question is, would the estimated years still hold if the surname was completely different and the earliest known ancestors were hundreds of miles apart?

  23. I did a Y67 test in January. I have only 12 matches, the closest at a genetic distance of 4 (i.e. 10+ generations). Given that I have no close matches, is there any benefit in doing further testing such as Big Y?

  24. One of the reasons some tests have very few matches is because there are very few people of that y-DNA line who have been tested. Most of the DNA test are from the USA; if an ancestor immigrated late [say after 1900] and/or had few descendants, that can explain why there are few matches. I recently tested an in-law’s relative and he only had 2 matches on a 37 test. However in the 1940 census in the city where he lived, there was 1 man who fit DNA match name and age. That family had immigrated in the early 1900’s from Poland. Very few DNA tests have been done on Polish residents, but his ethnic makeup fit that one name and family’s history. I’m certain it was his ancestral line. DNA + records is how you can pinpoint family. Just remember the pool comes from folks who have tested and some families have done more tests while others have not [fro a variety of reasons]. Keep checking your results as you will likely acquire more as more get tested; it won’t likely stay the same.

    • Not for quality. It is a challenge for genealogy, but there is a very active Swedish DNA project at Family Tree DNA that is extremely helpful. I suggest joining after you test or when you place your order.

  25. Pingback: Big Y-500 STR Matching | DNAeXplained – Genetic Genealogy

  26. Roberta

    What would the Big Y-700 (which would cost US$649) provide me that would give more information than doing a full genome sequence, (eg) Dante Lab’s standard “Whole Genome Sequencing Full DNA TEST (30X)” costing 499 euros or “Whole GenomeZ – Whole Genome for Advanced Analysis (130X + 30X)”, 899 euros?

    • The Big Y has been dramatically reduced in price since that time and is less than the Dante Labs test – under $400 but I can’t remember the exact $ amount off the top of my head. However, to answer your question a different way, the only way you can be in the Y DNA matching database that is the largest in the world is to take the Big Y test at Family Tree DNA. Dante doesn’t provide any tools either, so you’ll need to work with another entity to obtain Y results sifted out from the rest. Some people didn’t receive their results for nearly a year from Dante.

      • Thanks Roberta

        The quote for Big Y-700 came from FT-DNA’s Big Y expert on 6 Feb 2020, and is for someone who has not taken any Y test, like me ($649 – I assume she is talking US$). My brother could upgrade for US$339 from a Y-37. My Campey relative could upgrade from a Y-67 for US$279.
        Can Dante’s results be imported into FT-DNA? Your answer implies not.

  27. Hi,
    What I can not find on this site and anywhere else, at present, is why someone would take a lower test than the Big-Y. I am wary of spending big money on a test at this time but I could afford a 67 or 111. Is this a waste of time? If so, why are people selling it – are they just making money from it?

    • 67 and 111 panels are for matching in a genealogical timeframe. The Big Y adds to that SNP testing at the highest resolution possible. Not everyone wants or needs that. Some people just want to know who they match for genealogy. You can always upgrade later if you want to.

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