scale lumber sizes - Model Railroader Magazine

If you divide 1 inch by 87.1 ( the scale ratio for HO scale ) you get 1 HO inch is equal to 0.0115 actual inches.

So that Evergreen styrene lumber, at 0.022" x 0.043" actual, is about as close to an scale "two by four" as you're likely to get. It scales out to being a scale 1.9 inches by 3.75 inches. Pieces with other dimensions will be similar in their degree of approximation.

Working in O scale, as I do, I don't sweat over whether it's nominal or dimensional lumber. I always use dimensional lumber, i.e., a scale 2 inches by scale 4 inches. It simplifies the math a little, and I doubt whether anyone else would notice a difference that tiny.

In HO scale, the half inch difference between nominal and dimensional lumber would only be 0.006 real inches. You'd need a good caliper, and good shop technique, to be able to measure that small a dimension. I don't think most people can look at a piece of styrene or wood and know without measuring that it's off by a small fraction. That's why we use scale rulers.

-Ed

Five out of four people have trouble with fractions. -Anonymous
Three may keep a secret, if two of them are dead. -Benjamin Franklin
"You don't have to be Jeeves to love butlers, but it helps." (Followers of Levi's Real Jewish Rye will get this one) -Ed K
 "A potted watch never boils." -Ed Kowal
If it's not fun, why do it ? -Ben & Jerry