Hmm, and one could extend this chunking approach to Maze62. Consume 12 bits (aka two base64 integers), but if the resulting number is in the range [62^2=3844 t

Hmm, and one could extend this chunking approach to Maze62. Consume 12 bits (aka two base64 integers), but if the resulting number is in the range [62^2=3844 to 64^2-1=4095] or [0 to 64^2-62^2-1=251], then add that extra quotient bit to the next input (from which you'll consume only 11 bits). That would make the worst case only take 12/11ths as long, or 109%, instead of 6/5ths as long, or 120%, as the best case (which would be the same as before). One could extend it upwards as far as desired (probably approaching log_64(62) worst-case and average-case space compared to base64[1]), though the integer arithmetic would become a pain eventually. 12/11 or maybe 18/17 (105.8%) or 24/23 (104.3%) is probably good enough for most purposes. The relatively hardcore might use 60/59 (101.7%), which x86_64 machines can still do with CPU arithmetic (an integer multiply of two 64-bit integers stores the results in two 64-bit registers, and you can then do an integer divide on that, which stores the quotient and remainder in those registers). [1] Average case: I analyze it like this. If you encode n base64 integers at a time, then you'll encode 6n bits at a time, but 6n-1 bits if you're unlucky and get a number in the ranges [62^n, 64^n - 1] or [0, 64^n - 62^n - 1]. These two ranges, taken together, make 2 * (64^n - 62^n) numbers out of 64^n possible n-digit base64 numbers. Thus, on average, you encode 6n - 1 * [2 * (64^n - 62^n)]/64^n = 6n - 2 * (1 - (62/64)^n) bits for every group of n characters, or 6 - 2/n * (1 - (62/64)^n) bits per character. (Note that this analysis only applies while 62^n < 64^n < 2 * 62^n, so taking n -> ∞ gives misleading results.) The original Maze62 proposal has n = 1, and this yields 5.9375 bits per character on average, which is pretty good. (Check this: 5 * 4/64 + 6 * 60/64 = 5.9375.) The next few values are: 1 5.9375 2 5.9384765625 3 5.939432779947917 4 5.940369129180908 ... 10 5.945595231334425 Theoretical limit: 6 * log_64(62) = 5.954196310386876 So I guess there's really not much to be gained for the average case by increasing n. But someone pointed out that all-0 and all-1 sequences happen frequently in real situations, so it may be worth it anyway.