geohash string length and accuracy

Question

if length of geohash string is more, it is more accurate. But is there any direct relationship like if length is 7 it is providing 100 meter accuracy,

i.e. if two

Answer 1

Here are the formulas for height and width in degrees of a geohash of length n characters:

First define this function:

    parity(n) = 0 if n is even otherwise 1

Then

    height = 180 / 2^{(5n-parity(n))/2} degrees

    width = 180 / 2^{(5n+parity(n)-2)/2} degrees

Note that this is the height and width in degrees only. To convert this to metres requires that you know where on the earth the hash is.

Code for this in java is at http://github.com/davidmoten/geo.