Zoom levels - OpenStreetMap Wiki

The "# Tiles" column indicates the number of tiles needed to show the entire world at the given zoom level. This is useful when calculating storage requirements for pre-generated tiles. The "° Tile width" column gives the map width in degrees of longitude, for a square tile drawn at that zoom level. Values listed in the column "m / pixels" gives the number of meters per pixel at that zoom level fo

[kenzan8000]

number of map tiles per zoom level, example the level represents, etc