If you have a calculator its not too hard.
real size / 87 = scale size
For example
14" / 87 = 0.161" (in ho)
12" / 87 = 0.138" (in ho - .013" over 1/8")
Some vendors sell strip wood in actual HO sizes.
Regards,
Charlie Comstock
http://www.kapplerusa.com/y2k/p-ho-12.htm
Here's a site with size charts in case you hate math...
The formulas are:
For conversion from inches to feet or inches in HO:
(inches/12) x 87 = feet in HO
For inches (less than 1 ft.) multiply the above answer times 12
You can set up a conversion chart on Xcel using this formula.
I generally use rulers that measure in tenths, rather than 16ths or eights of an inch; this makes things a little cleaner.
I hope this will help