🧬 Centimorgan to Relationship Lookup Calculator

Enter the total shared centimorgans (cM) from your DNA match to see possible relationship categories. These ranges are general references based on typical shared-DNA amounts — many relationships overlap in range, so always combine this with other genealogical evidence (family trees, shared matches, documents) to confirm an actual relationship.

Shared centimorgans (cM)

How the lookup works

Your total is tested against eight overlapping bands and every band that contains it is returned, with duplicate labels merged. Nothing is ranked or scored:

3,400-3,720  parent / child
2,300-3,400  full sibling, grandparent, aunt or uncle
1,300-2,300  half sibling, grandparent, aunt or uncle, high 1st cousin
  575-1,330  1st cousin, half aunt or uncle, great-grandparent
  200-  850  1st cousin once removed, half 1st cousin, high 2nd cousin
   90-  480  2nd cousin, 1st cousin twice removed, half 1C1R
   45-  235  2nd cousin once removed, half 2nd cousin, high 3rd cousin
    0-  190  3rd cousin or more distant

Enter 230 cM and three bands claim it at once, so nine relationships come back, from first cousin once removed down to third cousin. The bands are observed distributions of what real testers shared, of the kind published in the Shared cM Project, and were never meant to partition the number line.

Turning a list into an answer

A cM figure narrows the field; it never proves a relationship. Use shared matches, segment counts, ages and documented trees to choose among the names the tool returns.
Half and full differ by about half. A half first cousin averages roughly what a first cousin once removed does, which is why an unexplained low total often means a half relationship.
Endogamy pushes totals up. Where a population married within itself for generations, extra small segments accumulate from other lines and a distant cousin can read a band or two too close.

Only totals above 3,720 cM match no band. That usually means an identical twin, the same person tested twice, or a company counting fully identical regions differently.

Frequently asked questions

What relationship is 850 cM of shared DNA?

Six are possible: first cousin, half aunt or uncle, great-grandparent, first cousin once removed, half first cousin, or a high second cousin. 850 is the first cousin average, so that is where to start.

Why does one cM total return so many relationships?

Because the ranges overlap by nature. Two people related the same way can share very different amounts, so one total is consistent with several relationships.

Does a higher cM total always mean a closer relative?

On average yes, but not case by case. A generous second cousin can out-share a stingy first cousin once removed, and endogamy makes that common.