What is 1/8 inch scale?
At 1/8-inch scale (written 1/8" = 1'-0"), one-eighth of an inch on the drawing represents one foot in the real building. Because a foot is 12 inches, the drawing is 1:96 (12 ÷ 0.125 = 96). It reads at half the size of 1/4-inch scale, so it is common for whole-floor plans that need to fit on a sheet.
Source: Drafting scale (1/8" = 1'-0") · Verify against your AHJ and the adopted code edition.
At 1/8-inch scale — written 1/8” = 1’-0” — every 1/8 inch you measure on the drawing stands for 1 foot of the real building.
To get the ratio, put both sides in the same units. A foot is 12 inches, so:
12 ÷ 0.125 = 96 → the drawing is 1:96
A few things that follow:
- It’s half the size of 1/4-inch scale (1:48). Swap a 1/4” plan to 1/8” and it takes up a quarter of the paper area — handy for fitting a whole floor on one sheet.
- Reading it: 1 foot = 1/8”, so 8 feet = 1 inch. A wall that measures 3 inches on the sheet is 24 feet long.
- On an architect’s scale, use the edge marked 1/8; the tick marks at the zero end read off the inches.
Work it out: the architectural scale converter turns a measured drawing length into the real dimension at 1/8”, 1/4”, or any scale — and back again.