GPS Coordinate Precision Calculator
The number of decimal places in a latitude or longitude value sets how finely it can locate a point on the ground. Each decimal place increases resolution tenfold. This calculator converts a decimal place count into ground precision in metres for both latitude and longitude at your chosen latitude, where longitude precision tightens with the cosine of the latitude. Use it to decide how many decimal places to store and to understand what a coordinate's stated precision really means.
GPS precision formula
degree step = 10 ^ (-decimal places)
latitude precision = degree step * metres per degree
longitude precision = degree step * metres per degree * cos(latitude)
Each decimal place is one power of ten of angular resolution. Multiplying the angular step by the metres per degree of latitude gives the north-south ground precision. The east-west precision is the same step scaled by the cosine of the latitude, reflecting meridian convergence toward the poles.
Worked example
At 5 decimal places, latitude 40 degrees and 111,320 m per degree: the degree step is 0.00001, so latitude precision is 0.00001 times 111,320 = 1.11 m. Longitude precision is 1.11 times cos(40) = 0.85 m. So a coordinate written to 5 decimal places pins a location to roughly one metre at this latitude.
GPS precision: frequently asked questions
How does decimal place count relate to GPS precision?
Each additional decimal place on a latitude or longitude value divides the ground resolution by ten. One degree of latitude is about 111,320 m at the WGS84 mean, so 5 decimal places (1e-5 degree) is roughly 1.11 m of latitude precision. Longitude precision shrinks with the cosine of latitude.
Why does longitude precision depend on latitude?
Lines of longitude (meridians) converge toward the poles, so a degree of longitude covers less ground the further you are from the equator. The east-west distance per degree is roughly 111,320 m times the cosine of the latitude, becoming zero at the poles.
What value is used for a degree of latitude?
This calculator defaults to 111,320 m per degree, the commonly used WGS84 mean metres per degree of latitude. It is an editable input. The true figure varies slightly from about 110,574 m at the equator to 111,694 m at the poles because the Earth is an oblate spheroid.
How many decimal places do I actually need?
Six decimal places (about 0.11 m of latitude precision) is finer than consumer GPS accuracy, which is typically a few metres. Five decimal places (about 1.11 m) is usually sufficient for mapping; more places store noise, not real precision.
Sources and references
- U.S. Government GPS information: GPS accuracy and performance.
- National Geospatial-Intelligence Agency: WGS84 reference.
- Formula: WGS84 metres-per-degree geometry; longitude scaling by cosine of latitude.
Reviewed by the CalculatorHub team, edited by James Graham, 19 June 2026. See our methodology.