Estimating the number of tiles and size on disk

Please download one of the attached spreadsheets (Open Document or Excel 97).

The green areas in the document are numbers you should change to match your data. When you specify the bounds, use the extent of your actual data, what is known as "dataBounds" in GWC 1.1.x or as gridSubset in GWC 1.2.x. Using the world bounds represents the worst case scenario.

Note that the numbers are for each zoomlevel, but the error margins are so large that this is not significant.

Preview

To cover the entire planet is quite resource intensive. Assumptions:

• Bounding box: -180,-90,180,90 (EPSG:4326)
• Average tile size: 20 kbyte (typical for PNG with some antialiasing, or JPEG of raster)
• Response time from WMS for 768x768 GetMap?: 0.5
• Number of cores on WMS server: 2
• Tile dimensions: 256x256 pixels

Please note that these numbers below in many ways represent the worst case scenario. Speak to an expert before using the attached spreadsheet as a decision tool.

Zoomlevel	Number of tiles	Disk space (megabytes)	Time to render (hours)	Note
0	2	0	0
1	8	0	0
2	32	1	0
3	128	3	0
4	512	10	0
5	2,048	40	0
6	8,192	160	0
7	32,768	640	0
8	131,072	2,560	1
9	524,288	10,240	4
10	2,097,152	40,960	16
11	8,388,608	163,840	65
12	33,554,432	655,360	259	This is 11 days of rendering
13	134,217,728	2,621,440	1,036	This is 2 terabytes
14	536,870,912	10,485,760	4,143
15	2,147,483,648	41,943,040	16,570	This is two years of rendering
16	8,589,934,592	167,772,160	66,280
17	34,359,738,368	671,088,640	265,121
18	137,438,953,472	2,684,354,560	1,060,486	This is 2.7 petabytes
19	549,755,813,888	10,737,418,240	4,241,943
20	2,199,023,255,552	42,949,672,960	16,967,772