Architectural scale converter
Convert between drawing and real sizes at any scale, metric or imperial.
How it is calculated
Real size = drawing size × scale factor. At 1:100, 10 mm on paper is 1,000 mm real. Imperial scales convert to ratios: 1/4" = 1'-0" is 1:48. Moving a drawing from one sheet to another multiplies the scale by the ratio of the sheet widths.
Questions
What ratio is 1/4" = 1'-0"?
1:48, because one foot is 12 inches and 12 ÷ 0.25 = 48.
What scale does an A1 drawing at 1:100 become on A3?
1:200. A3 is half the width of A1.
Is anything I enter saved or sent?
No. The calculation runs in your browser. Nothing you type is sent anywhere. You can copy the result, print it or download it as a CSV.