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Drawing Scale Chart: Architectural, Engineering, and Metric Scales
A drawing scale tells you how much real distance each unit on the paper stands for. On a 1/4 inch scale floor plan, 1/4 inch on the page is one foot in the house. The charts below list every common scale with its ratio and what it is used for, and each links to a full conversion chart.
Architectural scales list
Used on floor plans, elevations, and details in the U.S. Each one says how much paper stands for one real foot.
| Scale | Ratio | 1 inch on paper | Used for |
|---|---|---|---|
| 1/32" = 1'-0" | 1:384 | 32' | key plans and overall plans of very large buildings and campuses |
| 1/16" = 1'-0" | 1:192 | 16' | overall plans of large buildings and key plans that show a whole floor on one sheet |
| 3/32" = 1'-0" | 1:128 | 10' 8" | large floor plans and overall plans when 1/8 inch scale will not fit the sheet |
| 1/8" = 1'-0" | 1:96 | 8' | floor plans of larger homes and commercial buildings |
| 3/16" = 1'-0" | 1:64 | 5' 4" | floor plans and elevations when a 1/4 inch plan is too big for the sheet |
| 1/4" = 1'-0" | 1:48 | 4' | residential floor plans and exterior elevations |
| 3/8" = 1'-0" | 1:32 | 2' 8" | enlarged plans of rooms such as kitchens and bathrooms |
| 1/2" = 1'-0" | 1:24 | 2' | enlarged plans |
| 3/4" = 1'-0" | 1:16 | 1' 4" | wall sections and larger construction details |
| 1" = 1'-0" | 1:12 | 1' | construction details such as stair sections |
| 1-1/2" = 1'-0" | 1:8 | 8" | construction details that need to show individual boards |
| 3" = 1'-0" | 1:4 | 4" | full construction details such as millwork |
Engineering (civil) scales list
Also called civil scales. Used on site plans, surveys, and road and grading drawings. Each one says how many real feet one paper inch stands for, so a site plan at 1" = 20' shows 20 feet of ground in every inch.
| Scale | Ratio | 1 inch on paper | Used for |
|---|---|---|---|
| 1" = 10' | 1:120 | 10' | site plans for single lots |
| 1" = 20' | 1:240 | 20' | site plans for residential and small commercial lots |
| 1" = 30' | 1:360 | 30' | site plans for larger lots and small commercial developments |
| 1" = 40' | 1:480 | 40' | civil site plans |
| 1" = 50' | 1:600 | 50' | subdivision plans and site plans for large commercial properties |
| 1" = 60' | 1:720 | 60' | subdivision plats |
| 1" = 100' | 1:1200 | 100' | overall site plans |
Metric scales list
Used on drawings almost everywhere outside the U.S. A ratio like 1:50 means one unit on paper is 50 of the same unit in real life.
| Scale | 1 cm on paper | Used for |
|---|---|---|
| 1:10 | 10 cm | construction details such as wall junctions |
| 1:20 | 20 cm | construction details |
| 1:25 | 25 cm | details |
| 1:40 | 40 cm | school scale drawing exercises and some interior layouts |
| 1:50 | 50 cm | house floor plans |
| 1:100 | 1 m | floor plans and elevations of larger buildings |
| 1:150 | 1.5 m | plans of buildings too big for a 1:100 sheet that would lose detail at 1:200 |
| 1:200 | 2 m | building plans of large projects and site plans of smaller sites |
| 1:250 | 2.5 m | site plans and overall plans of large buildings |
| 1:500 | 5 m | site plans and block plans that show a building on its plot |
| 1:1000 | 10 m | location plans and maps that show a site in its surroundings |
What scale are floor plans drawn at?
Most U.S. house plans are drawn at 1/4 inch = 1 foot, so a 12 foot wall is 3 inches long on the page. Larger homes and commercial buildings often use 1/8 inch = 1 foot to fit the sheet. Metric plans are usually 1:50 for a house and 1:100 for larger buildings. The scale is printed in the title block or under the drawing. The floor plan scale guide covers how to read it and what to do when it is missing.
What does 2:1 scale mean?
A 2:1 scale drawing is twice real size: 2 cm on the page is 1 cm on the object. The bigger number comes first, so these are enlargement scales, the opposite of 1:50 or 1:100. Scales like 2:1, 5:1, and 10:1 are used for small parts, hardware, and fine details that would be too small to read at full size. Floor plans and site plans are never drawn this way.
Measuring a plan without a scale ruler
The floor plan scale calculator converts between paper and real measurements for any scale. To see what the measurements mean for a room, the room size chart and the square footage chart put common sizes in context.
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