rpgman2013 , the best way to get the proper approximation is to measure a long stretch of distance. Example: 20 hexes. Then divide that by the result of the ruler. Step 1: Measure the straight line (horizontal or vertical) distance out to 20 hexes. At scale = 1 and unit = 1 for Hex (V) I got 20/21.5 = ~0.93 Step 2: Measure the diagonal disttance out to 20 hexes. At scale =1 and unit = 1 for Hex (V) I got 20/21.9 = ~0.913 Step 3: Decide which direction you want to be most accurate or split the difference. In this case splitting the difference gives me ~0.9215. Step 4: Set the scale to the desired value. Note: I split the difference and then I mentally round up or down. It will be so close that over the 20 hexes of distance the ruler is only off by only +/-0.2 in either direction. - Gauss