Google Maps Tile Scales

I found this buried deep in an appendix of the Mapnik XML Schema Reference, and I thought it so useful I am reposting it here:

Zoom level	Scale denominator
0	559,082,264
1	279,541,132
2	139,770,566
3	69,885,283
4	34,942,642
5	17,471,321
6	8,735,660
7	4,367,830
8	2,183,915
9	1,091,958
10	545,979
11	272,989
12	136,495
13	68,247
14	34,124
15	17,062
16	8,531
17	4,265
18	2,133
19	1,066
20	533

These are used not only by Google Maps, but also by Bing Maps, OSM, CloudMade and many others, and in fact just about any Google Mercator tile source.