Geohash Precision Calculator
A geohash encodes a location as a short string; longer strings mean smaller cells. Each base-32 character contributes 5 bits, alternating between longitude and latitude. This calculator turns a geohash length into the number of bits per axis, the cell width and height in degrees, and the cell size in metres at your latitude. Use it to choose a geohash length that matches your required precision before indexing or bucketing points.
Geohash precision formula
total bits = 5 * length
lonBits = ceil(total bits / 2), latBits = floor(total bits / 2)
cell width deg = 360 / 2^lonBits
cell height deg = 180 / 2^latBits
cell width m = width deg * metres per degree * cos(lat)
cell height m = height deg * metres per degree
Bits are dealt longitude first, so odd total-bit counts give longitude the extra bit. Each axis cell spans the full range (360 for longitude, 180 for latitude) divided by two raised to its bit count. Metres come from the metres-per-degree figure, with longitude scaled by the cosine of latitude.
Worked example
Length 6: total bits = 30, lonBits = 15, latBits = 15. Width = 360 / 32,768 = 0.010986 degrees, height = 180 / 32,768 = 0.005493 degrees. At latitude 40 and 111,320 m/degree: width = 0.010986 times 111,320 times cos(40) = 937.18 m, height = 0.005493 times 111,320 = 611.55 m. That matches the well-known roughly 1.2 km by 0.6 km size for a 6-character geohash near the equator, shrinking with latitude.
Geohash precision: frequently asked questions
What is a geohash?
A geohash is a short string that encodes a latitude/longitude region. Each base-32 character adds 5 bits, alternately subdividing longitude and latitude. Longer geohashes describe smaller cells, so the string length sets the spatial precision.
How is the cell size found from geohash length?
Each character adds 5 bits, split between longitude and latitude (3 and 2, then 2 and 3, alternating). After n characters with lonBits longitude bits and latBits latitude bits, the cell spans 360 / 2^lonBits degrees of longitude and 180 / 2^latBits degrees of latitude. Multiplying by metres per degree gives the cell size in metres.
Why are geohash cells not square?
Because the 5 bits per character do not split evenly between the two axes, and because a degree of longitude is shorter than a degree of latitude away from the equator. The calculator shows width and height separately at your chosen latitude.
How long should my geohash be?
A 6-character geohash is roughly a 1.2 km by 0.6 km cell, good for neighbourhood lookups. An 8-character geohash is about 38 m by 19 m, fine enough for a single building. Pick the shortest length that meets your precision need.
Sources and references
- U.S. Government GPS information: coordinate systems and precision.
- National Geospatial-Intelligence Agency: WGS84 reference.
- Formula: standard base-32 geohash bit-interleaving geometry.
Reviewed by the CalculatorHub team, edited by James Graham, 19 June 2026. See our methodology.