The length of the flag should be at least 1/4 the height of the flagpole. For example, a 40' flagpole requires a 6' x 10' flag or larger. This guideline applies to flagpoles 20' and larger. Most residential flags are 3' x 5' or 4' x 6'. Most small industrial and commercial buildings use either a 5' x 8' or a 6' x 10' flag. Major industrial, municipal and government buildings require 8' x 12' and larger. However, the size of the flagpole is the determining factor.

20' ........................................3' x 5', 4' x 6'
25' ........................................4' x 6', 5' x 8'
30'-35' .................................5' x 8', 6' x 10'
40'-45' ...............................6' x 10', 8' x 12'
50' ...................................8' x 12', 10' x 15'
60'-65' ............................10' x 15', 10' x 19'
70'-80' ............................10' x 19', 12' x 18'
90'-100' ...........................20' x 38', 30' x 50'