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1:20 Scale Explained

At 1:20, one unit on the drawing stands for 20 of the same unit in real life. So 1 cm on paper is 20 cm, and 1 m in real life is drawn 50 mm long.

What is 1:20 scale used for?

1:20 is used for construction details, interior elevations, and furniture layouts. Drawings at this scale are read with an scale ratio ruler marked in ratios, or with any metric ruler and a quick multiplication.

How many meters is 1 cm at 1:20?

At 1:20, 1 cm on the drawing is 20 cm in real life. Multiply any paper measurement by 20 to get the real size in the same unit.

How do I convert real size to 1:20?

Divide the real measurement by 20. A 5 m wall is 250 mm long on a 1:20 drawing.

How much fits on one sheet at 1:20?

An A1 sheet (841 x 594 mm) covers 16.82 m by 11.88 m of real space at 1:20, before margins and the title block. An A3 sheet (420 x 297 mm) covers 8.4 m by 5.94 m.

A 4 x 5 m room at 1:20

A bedroom 4 by 5 meters is drawn 200 by 250 mm at 1:20. That is why house plans use 1:50 or 1:100: rooms are big enough to label, and the whole floor fits on one sheet.

How to measure a drawing at 1:20

1. 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.
2. 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.
3. 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: 1:25. Every scale is compared on the drawing scale chart.