The space occupied by the map should be calculated as tabular lines. The number of tabular lines per inch depends on your paper’s type size and leading. Measure the number of lines per inch in a text notice printed in your paper. Most legal sections print between 8 and 12 lines per inch.
Measure the map after it is printed to determine its height in inches. Multiply the height by your paper’s lines per inch to determine the number of tabular lines occupied by the map, then multiply it by the number of columns and the legal rate per tabular line.
(Map’s height in inches) x (# lines per inch) x (# Columns) x (Legal rate per tabular line)