public static double metersPerPixelAtEquator(int zoom) {
    return WORLD_CIRCUMFERENCE_METERS / Math.pow(2d, zoom + 8d);
  }
Returns the width in meters of a single pixel of a 256x256 px tile at the given {@code zoom} level.
planetiler-core/src/main/java/com/onthegomap/planetiler/geo/GeoUtils.java