Inbreeding coefficient
Paste a pedigree and choose two animals. The tool gives the inbreeding coefficient of their offspring.
Nothing you enter is sent: your data stays on your device.
- PedigreePaste or import a CSV
- Mating to assessChoose the male and the female
- ResultCoefficient and diagram
Step 1 of 3
Pedigree
Your pedigree stays in this browser tab, even after a reload. Close the tab and it is gone; a new tab starts empty. A shared link carries the male and the female only, never the pedigree.
Leave the cell empty when a parent is unknown.
A CSV with the same three columns (id, sire, dam), chosen or dropped here. A first line may name the columns, in English or French. The file is read in your browser, never sent.
5,000 animals and 1 MB at most.
How it’s calculated
Method
Everything happens in your browser: the pedigree, the import, the calculation and the exports. Nothing is sent. Your pedigree stays in this tab and is gone when you close it.
The inbreeding coefficient F of a pup is the probability that its two copies of a gene come from one and the same copy in a common ancestor. It equals the coefficient of kinship of its two parents.
The tool computes it exactly, over the whole pedigree, with the tabular method: an animal’s kinship with another is the mean of its parents’ kinship with that other, and an animal’s kinship with itself is ½ (1 + F). The result is an exact fraction.
To explain it, the tool lists Wright’s paths: for each common ancestor, n1 generations separate it from the male and n2 from the female, with no animal passed twice.
F = Σ (1/2)^(n1 + n2 + 1) × (1 + F of the ancestor)
The paths add up to the tabular result; past 500 paths the list is cut, never the coefficient.
Limits
- Founders (animals with no known parent) are assumed unrelated and not inbred; an unknown parent counts as a founder.
- The result holds only for the pedigree entered: an ancestor missing from the list does not count.
- The reference values come from the calculation, they are not thresholds: none of the sources cited here sets an acceptable level.
Sources
- Wright S. (1922), Coefficients of inbreeding and relationship, The American Naturalist 56: the origin of the path method. We could not open the article: the formula above is written from Gardner and Yampolski’s worked examples, which attribute it to Wright (1922).
- Nilforooshan, Garrick and Harris (2021), Alternative Ways of Computing the Numerator Relationship Matrix, Frontiers in Genetics 12: the tabular method (section 3.1) the tool uses for the exact calculation.
- Gardner and Yampolski (2007), Evolution Module 6.5: Inbreeding, course notes, East Tennessee State University: Wright’s paths with no animal passed twice, an inbred common ancestor (× (1 + F of the ancestor)) and several common ancestors added up.
These tools help you plan. They replace neither your protocol nor your animal care committee.