The Bit.ly "puffer" fish is a very popular URL shortener mascot.
Ultra-popular URL shortener, Bit.ly is proud of not reusing its URL codes – those alphanumeric combinations after the domain.
The reason is simple: unlike other URL shorteners that use 3 or 4 digits that eventually expire in order to be reused, Bit.ly uses six slots that never expire.
Let’s do some math.
There are 26 letters and each one is used by Bit.ly in both its lowercase (a, b, c, etc.) and uppercase format (A, B, C, etc.). In addition to letters, Bit.ly also uses the numbers [0 – 9].
Therefore, the total number of “chips” is 62 (26 + 26 + 10)
Isn’t math great? But wait, that was only Math 101.
In order to calculate the total amount of permutations available to a 62 x 62 matrix, we have to raise the “chips” to the power of the number of slots available, in our case six.
So 62^6 becomes the number 56,800,235,584 or about 56 billion-something URLs.
In other words, popular Bit.ly won’t be needing to change its length any time soon.
