COI Calculator

Upload a pedigree JSON to calculate the coefficient of inbreeding (COI) for a horse or a planned pairing. The calculator runs entirely in your browser and shows which shared ancestors are driving the number.

Export your horse's pedigree JSON from its registry page, or build one manually. The JSON needs a name field at the top level and optional sire / dam objects nested inside.

Upload the pedigree JSON for a single horse to calculate its own coefficient of inbreeding.

Horse pedigree

Drop JSON here or click to upload

Pedigree tree format