How this calculator works
Merck gives lifespan ranges for budgies, finches and African greys, and up-to values for several other groups. The calculator shows which reference is used and allows a custom assumption. Range endpoints produce a range of human-age illustrations. Zebra finches use the broader finch reference; small conures use the Pyrrhura group. The 80-year human reference is a chosen round value, not a demographic claim.
Formula
Human illustration = bird age × chosen human lifespan / bird lifespan reference. Bird age and either lifespan can be reconstructed by rearranging the proportion. The ratio assumes linear scaling and has no biological validation.
Worked example
A five-year-old budgie compared with an 80-year human reference and a 5 to 10 year bird reference gives 40 to 80 illustrative human years; the 7.5-year midpoint gives 53.3333. A ten-year-old African grey with a 30 to 50 year reference gives 16 to 26.6667, with a central value of 20.
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Frequently asked questions
Does this establish when a bird is an adult?
No. Maturation and longevity vary by species and do not scale linearly with human age.
Why are some lifespan ranges a single value?
The source lists an up-to reference for those groups. It is shown openly rather than invented into a statistical range.
Can I use this for another species?
Choose custom and enter a supported lifespan assumption. The result remains an illustrative ratio, not an individual prognosis.