Founder Equivalents:
Founder equivalents estimates the expected number of equally contributing founders that would be required to produce the observed genetic diversity in the current population.

fe = 1 / Σ(pi2)

Where pi is the proportion of the genes of the living, descendant population contributed by founder i.

Founder Genome Equivalents:
Founder genome equivalents estimates the expected number of equally contributing founders that would be required to produce the observed genetic diversity in the current population if no alleles had been lost to drift.

fg = 1 / Σ(pi2/ri)

Where pi is the proportion of the genes of the living, descendant population contributed by founder i, and ri is the allelic retention for founder i (estimated by gene drop).

Lacy RC. 1989. Analysis of founder representation in pedigrees: founder equivalents and founder genome equivalents. Zoo Biol 8:111-123.