The COI (Coefficient of Inbreeding) is calculated up to a maximum of 12 generations. However, if a generation is found where fewer than 75% of the dogs in that generation are known, the calculation stops just short of that generation. So if all dogs are known in the 5th generation but only half of them are known in the 6th generation, a 5-generation COI will be calculated. For dogs with more than 10 generations of pedigree information available, a 10-generation COI is also calculated for comparison and statistical purposes.

The COI is calculated entirely from the pedigree information present in the database, so if there are inaccuracies in the pedigree, there will also be inaccuracies in the COI. COIs are calculated in batches weekly, so the current COI may not reflect recent pedigree changes. Accuracy of the COI is not guaranteed.