GeoJSON Coordinate Precision Reducer

Why Reduce Coordinate Precision?

GeoJSON coordinates often contain 15+ decimal places, far beyond what any real-world application needs. Each unnecessary decimal digit adds bytes to your file. Reducing precision to 6 decimal places (roughly 11 cm accuracy) can shrink file sizes by 20–40% with no visible impact on maps.

Precision Reference

How It Works

Set the desired number of decimal places using the control above, then paste your GeoJSON. Every coordinate in the output is rounded to the specified precision. All other data (properties, feature structure) is preserved exactly.

For additional file size reduction, combine precision reduction with geometry simplification or minification.

Try It

Paste this Point feature with high-precision coordinates and set the precision to 4 decimal places. The coordinates are reduced from 15 digits to 4:

Before (full IEEE 754 precision):

GeoJSON{
  "type": "Feature",
  "properties": { "name": "Central Park" },
  "geometry": {
    "type": "Point",
    "coordinates": [-73.965399742126465, 40.782901287078857]
  }
}

After (4 decimal places, ~11 m accuracy):

GeoJSON{
  "type": "Feature",
  "properties": { "name": "Central Park" },
  "geometry": {
    "type": "Point",
    "coordinates": [-73.9654, 40.7829]
  }
}

The coordinate -73.965399742126465 becomes -73.9654 — a reduction of 13 characters per number. For a FeatureCollection with thousands of coordinates, this adds up to significant file size savings.

IEEE 754 and Coordinate Precision

JavaScript stores numbers using the IEEE 754 double-precision format, which provides approximately 15–17 significant decimal digits. When GeoJSON is serialized with JSON.stringify, coordinates are written with all available digits by default — producing values like -73.965399742126465. Most of these digits are artifacts of binary-to-decimal conversion and do not represent real-world measurement accuracy.

GPS receivers typically achieve 3–5 meter accuracy (4–5 decimal places). Survey-grade equipment reaches centimeter accuracy (7–8 decimal places). Anything beyond 8 decimal places exceeds the precision of any terrestrial measurement system. Reducing to 6 decimal places (11 cm) is the standard recommendation for web mapping. Read more about coordinate conventions in the GeoJSON specification guide.