What scale is a house plan drawn at?
The short answer: 1/4" = 1'-0" in imperial practice, or 1:50 in metric. But the scale of a drawing is chosen, not fixed, and the choice follows from what the drawing has to show and what sheet it has to fit on.
What a scale actually is
A scale is a ratio between a distance on the paper and the same distance in the building. At 1/4" = 1'-0", a quarter of an inch on the sheet stands for a foot on site, so a 12 ft room is drawn exactly 3 inches long. Written as a pure ratio that is 1:48, because a foot is 48 quarter-inches.
The point of this is that a scaled drawing carries dimensions that nobody wrote down. Put a scale rule on the paper and you can measure a distance the draughtsman never annotated. That only works if the drawing was printed at true size — more on that below, because it is where most home-printed plans fall over.
The scales in ordinary use
| Imperial | Ratio | Metric equivalent | Used for |
|---|---|---|---|
| 1" = 40'-0" | 1:480 | 1:500 | Site and location plans |
| 1/16" = 1'-0" | 1:192 | 1:200 | A large building, or a block plan |
| 1/8" = 1'-0" | 1:96 | 1:100 | A whole house on A4; a large house on A3 |
| 3/16" = 1'-0" | 1:64 | — | A house on A3 when 1/4" will not fit |
| 1/4" = 1'-0" | 1:48 | 1:50 | The standard house plan scale |
| 1/2" = 1'-0" | 1:24 | 1:25 | One room, a kitchen or bathroom layout |
| 1" = 1'-0" | 1:12 | 1:10 | Details — a stair, a window head, a junction |
| 3" = 1'-0" | 1:4 | 1:5 | Large details and joinery |
Note that the imperial and metric columns are close but not equal. 1:48 is not 1:50, and a metric scale rule laid on an imperial drawing will read about 4% out. It matters on a long dimension.
Why 1/4" = 1'-0" won
It is the scale at which an ordinary house plan is legible without being unwieldy. A 40 ft wide house comes out 10 inches across — it fits comfortably on A3 or on US Arch B with room for dimension chains and a title block. Go smaller and door swings and wall thicknesses start closing up; go larger and the plan will not fit on a sheet you can hold.
For a small house or a flat, 1/8" = 1'-0" on A4 is perfectly readable and is what most estate agents and planning submissions use. For a single kitchen where you are setting out cabinets, go to 1/2" = 1'-0" — at quarter inch you simply cannot see the difference between a 600 mm and a 650 mm unit.
How to choose for your drawing
Work backwards from the sheet. Take the longest dimension of the building, divide it by the usable width of your paper after margins and the title block, and pick the nearest standard scale that is smaller than the answer.
Worked example. A house 44 ft long, printed on A3 (16.5" wide) with about 14" usable. At 1/4" = 1'-0" the plan is 44 × 0.25 = 11 inches — fits with room to spare, so use it. If the house were 64 ft, that becomes 16 inches and will not fit; drop to 3/16" (12 inches) or 1/8" (8 inches).
One more rule worth keeping: use a standard scale, never an arbitrary one. A drawing at "whatever fits" cannot be measured with a scale rule, and that is half the value of drawing to scale in the first place.
Printing so the scale survives
This is where scale is usually lost. In any print dialog:
- Set Scale to 100%. Never "Fit to page" or "Shrink to fit" — both silently resize the drawing by a few per cent, and a scale rule on that sheet will lie to you all the way through the job.
- Set Margins to None, so the printer does not shrink the page to fit its own unprintable border.
- Print at the paper size the sheet was laid out for. An A3 sheet sent to an A4 printer will be reduced whatever else you set.
- Check it. Put a ruler on a known dimension. If a wall marked 12'-0" measures 3 inches at 1/4" scale, the print is true.
Because of all this, a properly drawn sheet carries a graphic scale bar as well as the written scale. The bar is drawn in the same drawing, so if the print was scaled down, the bar was scaled down with it — measure against the bar and you get the right answer regardless.
DrawHousePlan prints at true architectural scale. Choose the scale for the sheet, and the plan comes out with its dimension chains, a scale bar, and a title block — so a ruler on the paper reads the real building. It also exports to PDF and to DXF for CAD. Free, no account, and the drawing never leaves your machine.