Hash collision probability calculator

While there are many resources describing in great detail mechanics of hash collisions and formulae for calculating it’s probabilities, I’m yet to find an easy to use, always available online interactive calculator that anyone could mess with to estimate their personal hashing needs. Well, here’s one…

Note that this is approximation which is very accurate for large numbers but will produce nonsense for unpracticable numbers like 2 items hashed into 1 bit.

This calculator is based on the hash collision probability formulae I gleaned from here

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  1. Hash size in bits: 1
    number of items hashed: 2

    probability of collision: 0.39…


    Check your base cases man.

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