Which formula did you use? There are various approximations. Although I got ~43 years using the one from https://en.wikipedia.org/wiki/Birthday_attack#Source_c

Which formula did you use? There are various approximations. Although I got ~43 years using the one from https://en.wikipedia.org/wiki/Birthday_attack#Source_code_example https://en.wikipedia.org/wiki/Birthday_attack#Source_code_ex... julia> birthday(prob, vals) = sqrt(2 * vals * -log1p(-prob)) birthday (generic function with 1 method) julia> iters = birthday(1/6e9, 2.0^132) 1.3471597122821932e15 julia> iters / 1e6 / 60 / 60 / 24 / 365 42.718154245376496