Practical guide · dimensions explained
Calculate a print scaling percentage with margins
Plan fit and fill between paper sizes while accounting for the usable area on the target sheet.
Reviewed September 28, 2026 · Worked examples calculated for this guide
Illustration of the related tool’s example; proportions only.
Keep all lengths in the same unit
Enter the source document’s full size, the target sheet size and the desired margin on each edge. Use one unit throughout. The usable width is target width minus twice the margin; the usable height is calculated the same way. A margin that consumes either dimension leaves no printable rectangle and is rejected.
Fit uses the smaller scale
Divide usable width by source width and usable height by source height. The smaller ratio keeps the entire page inside the usable target. For A4 at 210 × 297 mm going into A5 at 148 × 210 mm with zero margins, the width ratio is 148 ÷ 210, while the height ratio is 210 ÷ 297. Fit therefore gives approximately 70.4762%. This uses the nominal rounded millimeter sizes, rather than an idealized square-root ratio.
Fill uses the larger scale
The larger ratio covers all of the usable target but can crop the source. For a 200 × 100 mm source filling a 100 × 100 mm target, the scale is 100%. Half the source area lies outside the target. Fit instead uses 50%, leaving space above and below the 100 × 50 mm document. Both preserve the original shape.
Printer settings still matter
An 8 × 10-inch document fits at 100% inside an 8.5 × 11-inch sheet with 0.25-inch margins: the usable area is 8 × 10.5 inches. Your entered margin is a planning choice, not a claim that the printer can achieve it. In the print dialog, check the selected paper, orientation and scaling. A second automatic fit operation can alter the intended percentage.
Reference notes
References checked September 28, 2026. Calculations and worked examples are our own.