Maximum              Readable              Letter

Readable              Distance for          Height

Distance              Maximum

                        Impact

100’                   30’                     3”

150’                   40’                     4”

200’                   60’                     6”

350’                   80’                     8”

400’                   90’                     9”

450’                   100’                   10”

525’                   120’                   12”

630’                   150’                   15”

750’                   180’                   18”

1000’                  240’                   24”

1250’                  300’                   30”

1500’                  360’                   36”

1750’                  420’                   42”

2000’                  480’                   48”

2250’                  540’                   54”

2500’                  600’                   60”     

NOTE: The above distances will vary approximately 10% with various color combinations. 5,280’ equals 1 mile. Maximum distance colors are based on Red or Black on White background. Prepared by the California Institute of Technology.