Our kits use scale feet for the dimensions. Here’s how to convert the scale feet to inches.
Let say the kit shows 20 X 30 as the size. This is scale feet. To get inches from this start with the first number 20. Take 20 times 12 (which is how many inches there is in a foot) 20 X 12 = 240. Take the 240 and divide by 87 (for HO Scale) and you get 2.758. That’s right at 2-3/4 inches. Then take the 30 ( of the 20 X 30 ) and do the same thing. 30 X 12 = 360, then 360 divided by 87 (HO) which equals 4.137 Which is a little over 4-1/8 inch. So the kit would be 2-3/4 X 4-1/8 inches.
For N Scale divide by 160. So the 20 X 30 kit in N Scale would be 20 X 12 = 240, 240 divided by 160 would be 1.5 or 1-1/2 inches. Then the 30 X 12 = 360, 360 divided by 160 equals 2.250 or 2-1/4 inches. The kit in N Scale would be 1-1/2 X 2-1/4 inches.
Hope that helps.
Rick