Method & sources
Dogs
We use size-based conversion tables (small, medium, large). Lifespans are breed-level statistics.
Cats
The widely used conversion: 1 year = 15 human years, 2 years = 24, then about 4 human years per year.
Other animals
There is no standard conversion, so we map the age of maturity to human age 18 and the average lifespan to the average human lifespan (about 84), and interpolate in between. If the age of maturity is unknown, 20% of the lifespan is used.
For animals where only the maximum recorded lifespan is known (shown as "Longest recorded"), the record is mapped to human age 120.
All lifespan figures come from the sources listed on each page.
Data sources
Some lifespan data from AnAge (Human Ageing Genomic Resources), licensed under CC BY 3.0. We adapted the data (human-age conversions, fact summaries, unit conversions).
Tacutu R. et al. (2018) "Human Ageing Genomic Resources: new and updated databases." Nucleic Acids Research 46(D1):D1083-D1090.
Japanese names from Wikidata (CC0).