Interactive tool
Shared DNA Relationship Predictor
Enter a centimorgan amount from a DNA match and we'll return the set of plausible relationships, each with the cM range it covers. This is a genealogy tool, not a medical one — it never returns a single definitive answer.
One number, many possible relationships. Shared cM ranges overlap heavily for most relationships. Half-sibling, grandparent, and aunt/uncle, for example, are indistinguishable by cM alone. This tool returns the SET of plausible relationships for your input — never a single definitive answer.
Find this number in your DNA match's profile on AncestryDNA, 23andMe, MyHeritage, FamilyTreeDNA, GEDmatch or another matching service.
Source
Ranges are from The Shared cM Project (v4.0) (v4.0, March 2020), compiled by Blaine Bettinger and contributors. Citation:
Bettinger, B. (2020). The Shared cM Project Version 4.0. International Society of Genetic Genealogy (ISOGG) / dnapainter.com.
Important caveat: Shared cM ranges OVERLAP across multiple relationship types. A single cM number rarely identifies one relationship — it usually narrows the possibilities to a small set. Half-sibling, grandparent, and aunt/uncle ranges overlap heavily. Endogamous populations (Ashkenazi Jewish, Acadian, some Amish, isolated island groups) inflate apparent cM and may indicate a more distant biological relationship than the cM range suggests.
For more on how to interpret cM amounts, read our explainer at Understanding Centimorgans and the broader Ancestry & Genealogy pillar.
For background on centimorgans and DNA matching, read our explainers at Understanding Centimorgans, Shared DNA and Relationship Chart, and How DNA Matching Works. Back to the pillar: Ancestry & Genealogy.