THE TOOLKIT
Print scale calculator.
Find the percentage to fit one paper format inside another, without stretching the artwork.
The formula
Scale (%) = 100 × min(target width ÷ original width, target height ÷ original height)
Worked example: A4 to A3
A4 is 210 × 297 mm and A3 is 297 × 420 mm. The width ratio is 297 ÷ 210 ≈ 1.414286. The height ratio is 420 ÷ 297 ≈ 1.414141. Taking the smaller ratio gives 141.414…%, displayed as 141.4%.
The familiar ideal A-series enlargement is √2, about 141.421%. The slight difference comes from the whole-millimetre nominal dimensions. Our display rounds to one decimal place; a printer with integer-only controls may need a lower percentage to avoid clipping.
Does this rotate the page?
No. Both pages use portrait dimensions. If you rotate your artwork, compare the preview in your print dialogue before printing. Rotation can improve the available fit when converting between formats with different proportions.
Sources & method
- ISO 216:2007 · Source dimensions
- Adobe PDF page sizing · Fit, Actual size and Custom Scale options
Dimensions use the published nominal sizes. Conversions and calculator examples are derived from those values. Calculated results are estimates for planning, not printer calibration.
Keep things in proportion.
All print toolsPaper enlargement and reduction chart
Read across the row for your original format to the column for the destination. Every result is available without using the calculator.
| From / To | A0 | A1 | A2 | A3 | A4 | A5 | A6 | US Letter | US Legal |
|---|---|---|---|---|---|---|---|---|---|
| A0 | 100% | 70.63% | 49.94% | 35.315% | 24.97% | 17.598% | 12.447% | 23.498% | 25.671% |
| A1 | 141.379% | 100% | 70.63% | 49.94% | 35.315% | 24.915% | 17.598% | 33.222% | 36.346% |
| A2 | 200.168% | 141.428% | 100% | 70.707% | 50% | 35.238% | 24.915% | 47.037% | 51.404% |
| A3 | 283.095% | 200% | 141.414% | 100% | 70.707% | 49.831% | 35.238% | 66.523% | 72.693% |
| A4 | 400.336% | 282.857% | 200% | 141.414% | 100% | 70.476% | 49.831% | 94.074% | 102.809% |
| A5 | 566.19% | 400.476% | 282.857% | 200% | 141.428% | 100% | 70.476% | 133.047% | 145.878% |
| A6 | 800.952% | 565.714% | 400% | 282.857% | 200% | 140.952% | 100% | 188.783% | 205.619% |
| US Letter | 389.532% | 275.127% | 194.534% | 137.563% | 97.267% | 68.55% | 48.633% | 100% | 100% |
| US Legal | 334.364% | 236.501% | 167.041% | 118.11% | 83.52% | 59.055% | 41.619% | 78.571% | 100% |
The exact bound is 100 × min(destination width ÷ source width, destination height ÷ source height). Both formats stay in portrait orientation; this table does not rotate the artwork. Values are rounded down to at most three decimal places, so the displayed percentage never exceeds the exact nominal fit. A printer with fewer decimal places may need a further downward adjustment. The calculator's usual rounded display can differ slightly from this conservative table.
This is a fit inside the nominal sheet, not its printable area. It preserves proportions and can leave blank space. Printer margins, bleed, crop marks, manufacturing tolerances and borderless-driver enlargement need separate allowances. Choose the print provider's settings and measure a test print when the physical size matters.
ISO 216 defines the trimmed A-series scope. Adobe's A-series reference lists nominal millimetre dimensions; Adobe's US document reference gives Letter and Legal sizes. The percentages are Paper & Scale's calculations from those dimensions.
Download the underlying dimensions and scale matrix, or inspect the A4 and Letter comparison.