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1" = 20' Scale (1:240) Explained
At 1 inch = 20 feet, every inch on the drawing stands for 20 feet on the ground, a ratio of 1:240. A 100-foot property line is drawn 5" long.
What is 1" = 20' scale used for?
1" = 20' is used for site plans for residential and small commercial lots, and utility layouts. Drawings at this scale are read with an engineer's scale, or with a normal ruler and the conversion charts below.
What is 1" = 20' scale as a ratio?
1" = 20' is a ratio of 1:240. One unit on the drawing equals 240 of the same unit in real life, whether you measure in inches, feet, or anything else.
How many feet is 1 inch at 1" = 20'?
One inch on the drawing is 20' in real life. The chart below converts common paper measurements.
| On the drawing | In real life |
|---|---|
| 1/4" | 5' |
| 1/2" | 10' |
| 1" | 20' |
| 2" | 40' |
| 3" | 60' |
| 6" | 120' |
| 12" | 240' |
How do I convert real feet to 1" = 20'?
Divide the real length in feet by 20 to get inches on paper. A 250-foot lot line is drawn 12 1/2" long.
| In real life | On the drawing |
|---|---|
| 10' | 1/2" |
| 25' | 1 1/4" |
| 50' | 2 1/2" |
| 100' | 5" |
| 250' | 12 1/2" |
| 500' | 25" |
| 1,000' | 50" |
How much fits on one sheet at 1" = 20'?
A 24 x 36 inch ARCH D sheet covers 720 by 480 feet of real space at 1" = 20', before margins and the title block. A tabloid 11 x 17 sheet covers 340 by 220 feet.
A 12x16 room at 1" = 20'
A 12x16 room is drawn 5/8" by 13/16" at 1" = 20'. That is large enough to label the room and show doors, windows, and furniture.
How to measure a drawing at 1" = 20'
- Check the title block or scale bar to confirm the drawing really is 1" = 20'. Plans are often printed at a different size than they were drawn.
- Measure a dimension that is already labeled, such as an exterior wall, and compare it with the chart above. If they disagree, the print was scaled.
- For PDFs and images, skip the ruler. The floor plan scale calculator converts any measurement, and MeasureFloorPlan sets the scale from one known wall and measures every room from there.
More on reading scales: floor plan scale explained. Nearby scales: 1" = 10' and 1" = 30'. Every scale is compared on the drawing scale chart.
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