Construction drawing scale guide
Understanding architectural and civil engineering scales and when to use them.
What is drawing scale?
Scale tells you the relationship between the drawing and the actual building. A scale of 1/4" = 1'-0" means that every 1/4 inch on the drawing represents 1 foot in real life. Larger scales (like 1" = 1'-0") show more detail; smaller scales (like 1/8" = 1'-0") show larger areas.
Printed drawings may not be at true scale. Always use written dimensions. If a dimension is missing, submit an RFI, don't measure.
Architectural scales
Architectural scales use fractions of an inch to represent one foot. They're used for building drawings.
| Scale | Ratio | Typical Use |
|---|---|---|
| 1/16" = 1'-0" | 1:192 | Large site plans, campus plans |
| 3/32" = 1'-0" | 1:128 | Site plans |
| 1/8" = 1'-0" | 1:96 | Overall floor plans, site plans |
| 3/16" = 1'-0" | 1:64 | Floor plans (smaller buildings) |
| 1/4" = 1'-0" | 1:48 | Floor plans, elevations, sections |
| 3/8" = 1'-0" | 1:32 | Wall sections, interior elevations |
| 1/2" = 1'-0" | 1:24 | Interior elevations, enlarged plans |
| 3/4" = 1'-0" | 1:16 | Millwork details, cabinet elevations |
| 1" = 1'-0" | 1:12 | Large-scale details |
| 1-1/2" = 1'-0" | 1:8 | Connection details |
| 3" = 1'-0" | 1:4 | Very large details, profiles |
| Full Size | 1:1 | Actual size details |
Civil/engineering scales
Engineering scales use 1 inch to represent a number of feet. They're used for site plans, civil drawings, and surveys.
| Scale | Ratio | Typical Use |
|---|---|---|
| 1" = 10' | 1:120 | Site details |
| 1" = 20' | 1:240 | Small site plans |
| 1" = 30' | 1:360 | Site plans |
| 1" = 40' | 1:480 | Site plans |
| 1" = 50' | 1:600 | Large site plans |
| 1" = 100' | 1:1200 | Overall site plans |
| 1" = 200' | 1:2400 | Area maps, campus |
How to use an architect's scale
Look at the title block or below the drawing title for the scale (e.g., 1/4" = 1'-0")
Triangular architect scales have 11 different scales. Find the edge matching your drawing.
The large numbers are feet, the small divisions are inches. Count from the zero mark.
Measure a dimension you know (from notes) to verify the drawing is printed to scale.
Digital scale considerations
When working with PDFs or digital drawings:
- Check print settings, "Actual Size" or "100%" required; "Fit to Page" will distort scale
- Verify with scale bar, Many drawings include a graphic scale bar that stays accurate when resized
- Use calibrated PDF tools, Bluebeam and similar tools can calibrate to the drawing's stated scale. See our guide on how to mark up PDFs for more
- Note "Not to Scale" drawings, Sketches and diagrams may be labeled NTS
Keep exploring
Related references for reading and verifying construction drawings.