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1" = 40' Scale (1:480) Explained
At 1 inch = 40 feet, every inch on the drawing stands for 40 feet on the ground, a ratio of 1:480. A 100-foot property line is drawn 2 1/2" long.
What is 1" = 40' scale used for?
1" = 40' is used for civil site plans, grading, and drainage plans for commercial sites. Drawings at this scale are read with an engineer's scale, or with a normal ruler and the conversion charts below.
What is 1" = 40' scale as a ratio?
1" = 40' is a ratio of 1:480. One unit on the drawing equals 480 of the same unit in real life, whether you measure in inches, feet, or anything else.
How many feet is 1 inch at 1" = 40'?
One inch on the drawing is 40' in real life. The chart below converts common paper measurements.
| On the drawing | In real life |
|---|---|
| 1/4" | 10' |
| 1/2" | 20' |
| 1" | 40' |
| 2" | 80' |
| 3" | 120' |
| 6" | 240' |
| 12" | 480' |
How do I convert real feet to 1" = 40'?
Divide the real length in feet by 40 to get inches on paper. A 250-foot lot line is drawn 6 1/4" long.
| In real life | On the drawing |
|---|---|
| 10' | 1/4" |
| 25' | 5/8" |
| 50' | 1 1/4" |
| 100' | 2 1/2" |
| 250' | 6 1/4" |
| 500' | 12 1/2" |
| 1,000' | 25" |
How much fits on one sheet at 1" = 40'?
A 24 x 36 inch ARCH D sheet covers 1,440 by 960 feet of real space at 1" = 40', before margins and the title block. A tabloid 11 x 17 sheet covers 680 by 440 feet.
A 12x16 room at 1" = 40'
A 12x16 room is drawn 5/16" by 3/8" at 1" = 40'. At that size individual rooms are hard to label, which is why this scale is used for overall plans and sites rather than room layouts.
Is 1" = 40' the same as 1:500?
Close but not the same. 1" = 40' is 1:480, while 1:500 is a metric scale. Measuring a 1:500 drawing with a 1" = 40' scale rule is off by about 4%, which adds up fast on long walls.
How to measure a drawing at 1" = 40'
- Check the title block or scale bar to confirm the drawing really is 1" = 40'. 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" = 30' and 1" = 50'. Every scale is compared on the drawing scale chart.
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