The "Coefficient Of Inbreeding", or COI, commonly labeled F and expressed as a percent, is a measure of the amount of consanguinity in an individual's ancestry, in other words, how closely related offsprings parents are.
This tool allows you to calculate the inbreeding coefficient of a pedigree. Insert ancestor names or registration numbers in the pedigree form below, then press the "Calculate" button to get the inbreeding coefficient and breakdown. Blank fields will be ignored. Correct spelling is critical, as this program uses the entries to identify duplicate ancestors.
Important: The data you enter will not be saved automatically. To prevent data loss, save a configuration file before calculating the COI or refreshing the page.
Configuration: Copy/paste, or load, a saved pedigree config code:
|Save Configuration File:
A configuration file will be generated with the file name you enter here. Press the Save Settings button to save the file to your device. Example: my-pedigree.txt
|Load Configuration File:
Only a configuration file from this calculator will work. The pedigree will be automatically populated with ancestors from the configuration file. Select a configuration file from your device, then press the Load Settings button.
Simple examples of inbreeding coefficients.
These numbers are correct if the common ancestors themselves are not inbred. If they are, the inbreeding coefficient will be higher.
|Relationship between parents||Parents' common ancestor(s)||Inbreeding coefficient|
|Collaterally related parents|
|Both parents = grandparents||12.500%|
|Parent = grandparent||6.250%|
|Both parents = G-grandparents||6.250%|
|1st cousins||Pair of grandparents||6.250%|
|Parent = G-grandparent||3.125%|
|1st cousins once removed||Pair of grandparents = G-grandparents||3.125%|
|Half-1st cousins once removed||Grandparent = G-grandparent||1.563%|
|1st cousins twice removed||Pair of grandparents = 2G-grandparents||1.563%|
|2nd cousins||Pair of G-grandparents||1.563%|
|Half-1st cousins twice removed||Grandparent = 2G-grandparent||0.781%|
|2nd cousins once removed||Pair of G-grandparents = 2G-grandparents||0.781%|
|Half-2nd cousins once removed||G-grandparent = 2G-grandparent||0.391%|
|2nd cousins twice removed||Pair of G-grandparents = 3G-grandparents||0.391%|
|3rd cousins||Pair of 2G-grandparents||0.391%|
|Half-2nd cousins twice removed||G-grandparent = 3G-grandparent||0.195%|
|3rd cousins once removed||Pair of 2G-grandparents = 3G-grandparents||0.195%|
|Directly related parents|
|Self-fertilization, clones, or identical twins*||self||50.000%|
|Parent-offspring||self = parent||25.000%|
|Grandparent-grandoffspring||self = grandparent||12.500%|
|G-grandparent-G-grandoffspring||self = G-grandparent||6.250%|
*This is not possible in organisms such as mammals, in which the parents must be of opposite sexes.
Click a button to load a sample pedigree.