On average, if all tiles for an average US state were rendered at 15 zoom levels with default styles using Mapnik, how much would be the total used disk space by all PNG files? 200MB/500MB/1GB/5GB/1TB? I know for the whole world it is 20TB. asked 15 May '12, 19:26 LiveCarMap 
To get an estimate of the number of tiles you need to cover a state, go to map.geofabrik.de and activate the "tile coordinates" overlay (from the layer switcher in the top right corner of the map). Zoom in on the state you're interested in. You'll get something like this: So, Colorado for example has about one and half tiles on zoom level 6. The number of tiles quadruples for each zoom level, so you are looking at...
making a total of roughly 500k tiles. Now the average size of tiles is a tricky thing, it varies between zoom levels. But if your scenario includes tiles on higher zoom levels then the average size is surprisingly small  something like 2 kB. Tiles can easily reach 50kB and more but on high zooms, most of Colorado will likely be almost empty and the empty ones dominate the few large innercity tiles. (And, tile count wise, the higher zoom levels dominate the lower ones.) So the answer to your question is that for a state the size of Colorado and up to z15, you're probably looking at 2 kB * 500k tiles = 1 GB of tile storage. answered 12 Jun '12, 08:41 Frederik Ramm ♦ Thank you, this answers my question.
(13 Jun '12, 01:32)
LiveCarMap

You could also find the size of a single tile and then multiply that number for the area of the state that you are trying to cover. You just have to download the vector data and determine how far across a single tile is. Then find the x and y axis for the state and then finally multiply. It will be a rough estimate but still give you a baseline. Cheers, Nicholas answered 07 Jun '12, 22:00 ingalls 