How to use the drawing sheet size calculator
Choosing a sheet is one of the first decisions on a drawing set, and getting it wrong means rescaling views or splitting plans late in the job. This tool lists the standard ISO, ANSI and ARCH sheet sizes and, more usefully, works out which of them your drawing fits at a chosen scale, and what scale a particular sheet can take.
- Enter the real size of what you are drawing, in metres or feet: the overall plan, elevation or site extents, including dimensions and labels around it.
- Pick the scale, metric ratios or US architectural scales, which are shown as their ratio equivalents.
- Set a margin for each side that covers your border and title block.
- Choose a sheet to check to see whether the drawing fits it and the largest standard scale it allows.
The table below the results marks every standard sheet that fits, so you can see the smallest ISO, ANSI and ARCH option side by side.
Sheet size formulas
Paper size = real size ÷ scale ratio
Fits if paper size + 2 × margin ≤ sheet size (in either orientation)
Minimum scale ratio = max(real width ÷ usable width, real height ÷ usable height)
Real dimensions are converted to millimetres first (1 m = 1,000 mm, 1 ft = 304.8 mm), so a 30 m plan at 1:100 is 300 mm on paper. The fit check tries both landscape and portrait, and the minimum scale picks whichever orientation needs less reduction.
| Sheet | Millimetres | Inches |
|---|---|---|
| ISO A0 | 841 × 1189 | 33.1 × 46.8 |
| ISO A1 | 594 × 841 | 23.4 × 33.1 |
| ISO A2 | 420 × 594 | 16.5 × 23.4 |
| ISO A3 | 297 × 420 | 11.7 × 16.5 |
| ISO A4 | 210 × 297 | 8.3 × 11.7 |
| ANSI A / B / C / D / E | 216 × 279 to 864 × 1118 | 8.5 × 11, 11 × 17, 17 × 22, 22 × 34, 34 × 44 |
| ARCH A / B / C / D / E | 229 × 305 to 914 × 1219 | 9 × 12, 12 × 18, 18 × 24, 24 × 36, 36 × 48 |
| ARCH E1 | 762 × 1067 | 30 × 42 |
Worked examples
A house plan at 1:100
A ground floor plan 30 m wide and 18 m deep, with dimension strings, is 300 × 180 mm at 1:100. With 20 mm margins it needs 340 × 220 mm, so it fits on A3 (420 × 297 mm). The largest scale A3 allows is about 1:79, so the next standard scale, 1:100, is the right choice.
The same plan at 1:50
At 1:50 the plan becomes 600 × 360 mm, or 640 × 400 mm with margins. That is too wide for A2 (594 mm), so it goes on A1 (841 × 594 mm), which leaves room for a section or key plan beside it.
A US floor plan at 1/4" = 1'-0"
A 60 × 40 ft plan at 1/4" scale (1:48) is 15 × 10 inches. With 25 mm (about 1 inch) margins it just fits ARCH B (12 × 18 inches), but not ANSI B (11 × 17 inches), which is too short. In the ANSI series it jumps to ANSI C (17 × 22 inches). For a full set with title blocks, most US offices would use ARCH D instead.
Who this calculator helps
- Architects and technologists setting up sheet layouts and drawing scales for a set.
- Students planning portfolio and studio boards at a fixed scale.
- Interior designers fitting room plans and elevations onto presentation sheets.
- Consultants working across regions translating between ISO and US sheet sizes.
- Print and reprographics teams checking whether a file prints at true scale.
Tips for sheets and scales
- Keep one sheet size across a set; reduced A3 copies of an A1 set then read at exactly half scale.
- Measure drawing lengths and convert them at scale with the architectural scale converter.
- Switch between imperial and metric dimensions with the feet and inches converter.
- Always add a graphic scale bar, so a sheet printed at the wrong size can still be measured.
- Leave space for notes, legends and revision boxes; they take more room than expected.
Need a presentation image for the sheet? Turn a floor plan into a 3D view with Floor Plan to 3D.
