We measure how closely two people are related using units of measurement called centimorgans (cM). The number of centimorgans we report is our estimate of the amount of shared DNA we can attribute to a recent common ancestor.
For help with what relationship terms mean like "half aunt" and "third cousin once removed", see AncestryDNA® Match Categories.
Centimorgans (cM) as units of measurement
Centimorgans are units that measure the probability that a section of DNA will be passed on to a descendant intact (rather than being split into separate segments). One centimorgan represents a 1% chance that a section of DNA will split into separate segments (recombine) within a generation.
Centimorgans measure probability, not physical distance. Generally, the more centimorgans two people share, the closer they're related.
For more details about centimorgans, read our white paper on DNA matching.
Viewing shared centimorgans
In your match list, the second column shows the predicted relationship and amount of shared DNA (measured in centimorgans (cM)) with that match.
To see the other possible relationships based on the centimorgans, click the relationship link (like Father).
In the opened window, you’ll see how likely different relationships are between you and that match.
