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Laboratory Animal Sciences Program

Animal Numbers for Research Use

In an effort to assist investigators with determining the number of animals that are necessary to support their breeding studies, LASP has designed this calculator for your use. Please fill in the applicable data below and the calculator will generate an approximate number of animals that will be required to fulfill your research objectives. For your convenience, this calculator can also be downloaded as an Excel spreadsheet.

See an example.

Mice/Year Homozygous Heterozygous Notes
Number of Breeding Females
Number of Breeding Males 1:1 Male/Female or 1:2 Male/Female Breeding Scheme
Total Cages Needed to Support Breeding Assume 3 Cages Per Breeding Pair/Trio (1 for Breeding Pairs/Trios and 2 for Weanlings)
Average Litter Size
Average Number of Litters/Female/Year
Divert to Breeders (%)
(ex: enter 10 for 10%)
Het Factor (0 or 0.5) 0=Homozygous; 0.5=Heterozygous
Use Factor (0 to 0.5) 0=All Mice are Used; 0.5=Only One-Half of Mice are Used
Total Number of Breeders Used Per Year Breeders are rotated on a Six Month Basis
Total Mice Generated Per Year
Mice Available for Study Per Year This figure is adjusted to account for (1) % diverted to breeders; (2) the heterozygosity factor; and (3) the sex factor

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