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 geohash (and either of their bounding box) is having first 7 char matching, both should be near 100 meter etc?

I am using geohash for finding, all near-by location for given geohash, with their distance

Also any directway to calculate distance between two geo-hash? (one way is to decode them to lat/lng, and then calculate distance)

Thanks

Answer 1

Was curious about this myself. If its any good to anyone I put together a spreadsheet here Not 100% sure its right - feel free to comment if you find a problem.

Judging by graph below, using 6 to 10 digits gives accuracy ~1km to ~1m at 60 degree lat.