What this calculator does
Solve two present ages from their sum and age difference, then project them to another year.
How it works
The calculator evaluates older = (sum + difference) ÷ 2; younger = (sum − difference) ÷ 2. Inputs are checked before calculation, and invalid values such as zero denominators or out-of-range selections produce a clear error instead of a misleading result.
Input query strings and outputs
Use an input name in this page’s URL as ?name=value, and join additional inputs with &. Portable shared links may instead use the compact ?ac= state parameter.
Input query strings
3-
?sumAges=Sum of present agesNumber · Required · Default: 50
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?ageDifference=Older minus youngerNumber · Required · Default: 10
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?yearsFromNow=Years from now (negative for years ago)Number · Required · Default: 5
Outputs
4-
olderAgeOlder person nowNumber · Primary output
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youngerAgeYounger person nowNumber
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olderProjectedOlder person at projected timeNumber
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youngerProjectedYounger person at projected timeNumber
Inputs and results
The inputs are Sum of present ages, Older minus younger, Years from now (negative for years ago). Results include Older person now, Younger person now, Older person at projected time, Younger person at projected time.