The Scale Card 1:87 HO Scale Ruler

(HO Scale)The Scale Rule (24" and 12" and 6")1:87.1 scale drawing to 8 scale feet on your scale model
Scale Accuracy of Rules
1:12 to 1/2" -- 1:20.3 - 1:48 to 1" -- 1:64 and 1:96 to 2"
1:144 to 3" -- 1:192 to 4" and the 1:87.1/1:160 to 3"/6"
12" Up/Down Scales
1:12 uses 1:24/1:48, 1:20.3 to 1:32 and 1:64 use 1:87.1/1:48
1:35 uses 1:76/1:48, 1:48 uses 1:87.1/1:72, 1:96 uses 1:192/1:144
1:192 uses 1:96/1:144, and the 1:87.1/1:160 uses 24" of each