Coefficient Of Inbreeding Calculator

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 its parents are.

This tool allows you to calculate the inbreeding coefficient of a pedigree. Insert ancestor names 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 names to identify duplicate ancestors.

EDITING: ANCESTOR 1

Ancestor:
Ancestor Name:

SAVE CONFIGURATION

Configuration Name:

YOUR SAVED CONFIGURATIONS

Configuration Name	Action
None Saved

Comma-Delimited List Of Ancestors:

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
Siblings	Both parents	25.000%
Half-siblings	One parent	12.500%
Uncle-niece Aunt-nephew	Both parents = grandparents	12.500%
Half-uncle-niece Half-aunt-nephew	Parent = grandparent	6.250%
Granduncle-grandniece Grandaunt-grandnephew	Both parents = G-grandparents	6.250%
1st cousins	Pair of grandparents	6.250%
Half-granduncle-grandniece Half-grandaunt-grandnephew	Parent = G-grandparent	3.125%
Half-1st cousins	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%
Half-2nd cousins	G-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%
Half-3rd cousins	2G-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.