DNA match decoder

Shared cM calculator: how is this match related to you?

Enter the centimorgans (cM) you share with a match on Ancestry, MyHeritage, 23andMe, FamilyTreeDNA or GEDmatch. See every relationship that fits, and how well.

Shared cM Project v4 dataWorks with any DNA siteFree, no sign-up
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Where do I find my shared cM?

  • Ancestry: DNA Matches, open a match. The cM figure sits under the predicted relationship.
  • MyHeritage: DNA Matches, "Shared DNA" on each match card.
  • 23andMe: Relatives in DNA, open a profile. It shows a % and the cM beside it.
  • FamilyTreeDNA / GEDmatch: the "Shared cM" or "Total cM" column.

Shared cM chart: average and range by relationship

Each figure is the average and the observed range (min to max) of total shared cM, from tens of thousands of submitted relationships.

Parent or child

Parent / Child
3,4852,376-3,720

Full sibling

Full sibling
2,6131,613-3,488

Second-degree relatives

Half sibling
1,7591,160-2,436
Grandparent / Grandchild
1,754984-2,462
Aunt, Uncle / Niece, Nephew
1,7411,201-2,282

Third-degree relatives

Great-grandparent / Great-grandchild
887485-1,486
Half aunt, uncle / Half niece, nephew
871492-1,315
First cousin
866396-1,397
Great-aunt, uncle / Great-niece, nephew
850330-1,467

Fourth-degree relatives

Half first cousin
449156-979
First cousin once removed
433102-980
Half great-aunt, uncle / niece, nephew
431184-668
Great-great-aunt, uncle / niece, nephew
420186-713

Second cousins and equivalents

Second cousin
22941-592
Half first cousin once removed
22462-469
First cousin twice removed
22133-471
Half great-great-aunt, uncle / niece, nephew
208103-284

Second cousins once removed and equivalents

Half first cousin twice removed
12516-269
Second cousin once removed
12214-353
Half second cousin
12010-325
First cousin three times removed
11725-238

Third cousins and equivalents

Third cousin
730-234
Second cousin twice removed
710-244
Half second cousin once removed
660-190
Half first cousin three times removed
600-120

Third cousins once removed and equivalents

Second cousin three times removed
510-154
Third cousin once removed
480-192
Half third cousin
480-168
Half second cousin twice removed
480-144

Fourth cousins and equivalents

Half third cousin once removed
370-139
Third cousin twice removed
360-166
Fourth cousin
350-139

Fourth cousins once removed and equivalents

Fourth cousin once removed
280-126
Third cousin three times removed
270-98
Half third cousin twice removed
270-78

Fifth cousins and equivalents

Fifth cousin
250-117
Fourth cousin twice removed
220-93
Fifth cousin once removed
210-80
Fourth cousin three times removed
190-60

Sixth cousins and more distant

Sixth cousin
180-71
Fifth cousin twice removed
180-65
Sixth cousin once removed
150-56
Seventh cousin
140-57
Fifth cousin three times removed
130-30
Sixth cousin twice removed
130-45
Seventh cousin once removed
120-50
Eighth cousin
110-42

Ranges from The Shared cM Project v4 (March 2020) by Blaine T. Bettinger, CC BY 4.0. For relationships more distant than half second cousins the project sets the minimum to 0 cM.

Frequently asked questions

What is a centimorgan (cM)?+

A centimorgan is a unit of genetic length. DNA testing sites add up the length of every segment you and a match have in common, and that total shared cM is the best single clue to how you are related.

Why does one number fit several relationships?+

Relatives with the same expected amount of shared DNA overlap completely. A half sibling, a grandparent and an aunt all share about 1,750 cM on average, so the number alone cannot tell them apart. Ages, the match's own family tree and shared matches settle it.

Is this the probability that my match is a second cousin?+

No. The calculator shows which relationships have been observed at your number, and how central it is in each range. Real probabilities also depend on how many relatives of each kind you have, and everyone has far more distant cousins than close ones.

Where do the numbers come from?+

The Shared cM Project, Version 4 (March 2020), by genetic genealogist Blaine T. Bettinger, built from about 60,000 relationships submitted by people who knew how they were related. It is licensed CC BY 4.0.

My family is from an endogamous community. Does that change things?+

Yes. When families have married within the same community for generations (common in many South Asian, Jewish and island populations), people share extra DNA through many lines at once. Expect matches to look closer than they really are.

Is my data stored?+

The calculation runs in your browser. The number you enter may be logged to help us improve the tool, but it is never shown publicly. Saved matches stay in your own browser unless you email them to yourself.