Drawing scale calculator: find the scale that fits your sheet
Enter the real size of your plan and the sheet to get the largest standard scale that fits, convert lengths at any metric or imperial scale, and work out text heights for AutoCAD. Sheet sizes match our paper size viewer.
ISO A, ARCH and ANSI sheetsMargins and title block1:n, 1/4″ = 1′-0″ and 1″ = 20′Paper to real lengthText height and DIMSCALE
Calculator
What you are drawing
Sheet
0 if it sits inside the drawing area.
Scale
Metric, architectural or engineering. Pick Custom scale to type any other.
Type 1:75, 3/32" = 1'-0" or 1" = 25'.
Lengths
Type in either box; the other one updates. Feet-inches like 12' 6" work in ft.
AutoCAD units
Height on the printed sheet, in the layout unit.
Best scale
Largest standard scale that fits
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Every scale in this series
| Scale | Drawing on paper | Fits? |
|---|
Conversion
Real length
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This scale in other notations
Scale factor
Scale factor (DIMSCALE)
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Model text height for each plotted height
| Plotted height | On paper | Model text height |
|---|
Sheet sizes match our Paper Size Viewer (ISO 216, ARCH and ANSI, rounded to whole millimetres). Check the printable area of your plotter, which is usually a few millimetres inside the sheet edge.
Setting up sheets in Revit? Get title blocks and annotation families that are ready to plot.
Browse Revit familiesPick a scale in three steps
Describe the drawing
Enter the real width and depth of the plan, section or site in metres or feet, and choose metric, architectural or engineering scales.
Set up the sheet
Choose the sheet size and orientation, then the margin and title block width. The calculator works inside what is left.
Read the scale
You get the largest standard scale that fits, how much of the sheet it uses and a drawing of the sheet. Switch to the converter or text height tab for the same scale.
How drawing scale works
A scale of 1:n means 1 unit on paper stands for n units in reality. Divide the real size by n to get the size on paper, and multiply a measured paper length by n to get the real length.
Real length = paper length × n
a” = 1′-0″ is 1 : 12 ÷ a, so 1/4″ = 1′-0″ is 1:48
1″ = b’ is 1 : 12 × b, so 1″ = 20′ is 1:240
Worked example: a 30 × 20 m plan on an A1 sheet in landscape (841 × 594 mm) with a 10 mm margin leaves 821 × 574 mm. At 1:50 the plan is 30,000 ÷ 50 = 600 mm by 400 mm, which fits. At 1:25 it would be 1,200 mm wide, which does not, so 1:50 is the largest standard scale that fits.
Text height: for text that is not annotative, model text height = plotted height × n in the same unit. 2.5 mm text at 1:100 is 250 mm in a millimetre model, or 0.25 in a metre model.
Check the printable area of your plotter. Most printers cannot print the last few millimetres at the sheet edge, so a margin of at least 5 to 10 mm is a safe default.
Common drawing scales and their equivalents
| Scale | Ratio | Typical use |
|---|---|---|
| 3″ = 1′-0″ | 1:4 | Full-size and large details |
| 1 1/2″ = 1′-0″ | 1:8 | Details |
| 1:20, 3/4″ = 1′-0″ (1:16) | 1:20, 1:16 | Details and joinery |
| 1:50, 1/4″ = 1′-0″ (1:48) | 1:50, 1:48 | Floor plans, sections and elevations |
| 1:100, 1/8″ = 1′-0″ (1:96) | 1:100, 1:96 | General arrangement plans |
| 1:200, 1/16″ = 1′-0″ (1:192) | 1:200, 1:192 | Small-scale plans and key plans |
| 1:500, 1″ = 40′ (1:480) | 1:500, 1:480 | Site plans |
| 1:1250, 1:2500 | 1:1250, 1:2500 | Location plans |
| Sheet | Size |
|---|---|
| A1 | 594 × 841 mm |
| A3 | 297 × 420 mm |
| ARCH D | 24 × 36 in |
| ANSI B (tabloid) | 11 × 17 in |
The typical uses are a guide. Your client, office standard or local authority may ask for specific scales.
Drawing scale questions
Take the drawing area of the sheet, which is 841 × 594 mm in landscape less your margins and title block. Divide the real width and depth of the plan by each standard scale and pick the largest scale where both fit. A 30 × 20 m plan fits A1 at 1:50 (600 × 400 mm) but not at 1:25.
Multiply the length you measure on paper by 100. 45 mm on a 1:100 drawing is 4,500 mm, or 4.5 m. To go the other way, divide the real length by 100: 9 m is 90 mm on paper. Only measure from a print that was plotted at 100%.
1/4″ = 1′-0″ is 1:48, because one foot is 12 inches and 12 ÷ 1/4 = 48. In the same way 1/8″ = 1′-0″ is 1:96, 3/16″ = 1′-0″ is 1:64 and 1″ = 20′ on an engineering scale is 1:240.
No, but they are close. 1/4″ = 1′-0″ is 1:48, so a drawing at 1:48 is about 4% larger than the same drawing at 1:50. Never measure a 1:48 print with a 1:50 scale rule, or the reverse.
For a drawing in millimetres at 1:n, the scale factor and DIMSCALE are n, so text that should plot at 2.5 mm is 2.5 × 100 = 250 mm high at 1:100. For a model in metres with a layout in millimetres the factor is n ÷ 1000. In a viewport, type ZOOM 1/100xp for 1:100 in millimetres, or 1/48xp for 1/4″ = 1′-0″ in inches.
Plotted text of 2.5 mm, or 3/32″ in imperial, is the usual minimum for notes, with 3.5 mm or 1/8″ for headings and room names. Annotative text in AutoCAD and all annotation in Revit is set at the plotted height and scales automatically. Non-annotative text needs the plotted height times the scale factor.
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