Pattern Scaling Calculator
Resizing a sewing or craft pattern requires finding the scale factor, applying it to all dimensions, and then working out how to print the result. The scale factor is simply the ratio of the new size to the original size. If your pattern piece is 10 inches wide and you want a version that is 14 inches wide, the scale factor is 1.4, which means printing at 140 percent. Every other dimension on the pattern scales by the same factor, including lengths, curves, and notch positions. When the scaled pattern exceeds the size of a single sheet of paper, you tile it: print across multiple sheets and tape them together. This calculator supports Letter, A4, A3, and Tabloid paper and tells you exactly how many sheets you need in each direction. You can scale by specifying a new width, a new height, or a direct percentage. Seam allowances scale with the pattern; if you need a fixed seam allowance after scaling, trim the allowance from the original pieces before scaling and add the desired amount after. All dimensions are in inches.
Print at --% | New size: -- in wide x -- in tall
Scaling formulas
scale_factor = new_width / original_width (if scaling by width) scale_factor = new_height / original_height (if scaling by height) scale_factor = percentage / 100 (if scaling by percentage) new_height = original_height x scale_factor (when scaling by width) new_width = original_width x scale_factor (when scaling by height) print_percentage = scale_factor x 100
Tiling formulas
tiles_wide = ceil(new_width / paper_width) tiles_tall = ceil(new_height / paper_height) total_pages = tiles_wide x tiles_tall
Add a small overlap (typically 0.25 to 0.5 inches) when printing tiles so you can align and tape the sheets. Most PDF viewers and pattern apps offer a tiling option that handles overlap automatically.
Paper size reference
| Paper name | Width (in) | Height (in) | Typical region |
|---|---|---|---|
| Letter | 8.50 | 11.00 | United States, Canada |
| A4 | 8.27 | 11.69 | International |
| A3 | 11.69 | 16.54 | International |
| Tabloid / Ledger | 11.00 | 17.00 | United States |
Pattern scaling: frequently asked questions
How do I scale a sewing pattern to a different size?
Divide the desired new width (or height) by the original width (or height) to get the scale factor. Multiply all other dimensions by the same factor. For printing, multiply the scale factor by 100 to get the print percentage. If you know you want the pattern at 150 percent, set the scale factor to 1.5. This calculator does all three steps for you once you enter the original and target dimensions.
What does it mean to tile a pattern?
When a scaled pattern is larger than a single sheet of paper, it must be printed across multiple sheets that are then taped together. This is called tiling. The calculator tells you how many sheets wide and tall you will need, and the total page count. Print each tile with crop marks or overlap guides, then align and tape the sheets to assemble the full-size pattern.
What paper size should I use for printing patterns?
Letter (8.5 x 11 in) is standard in the United States. A4 (8.27 x 11.69 in) is the international standard used in most other countries. A3 and Tabloid (11 x 17 in) allow fewer tiles for large patterns. Some home printers only support Letter or A4; check your printer's maximum paper size before selecting a larger option.
How do I scale a pattern if I only know the percentage?
Select 'I know the percentage' from the scale method dropdown and enter the percentage. The calculator converts it to a scale factor and shows you the new width, new height, and tiling information. A percentage of 100 means no change; 200 means double size; 50 means half size.
Does scaling a pattern affect seam allowances?
Yes. Scaling a pattern proportionally scales everything, including any seam allowances printed on the pattern. If the original pattern has a 5/8-inch seam allowance and you scale to 150 percent, the seam allowance becomes 0.94 inches. If you want to preserve specific seam allowances, remove them before scaling (sew the seamline, not the cutting line) and add the desired seam allowance after scaling.
Sources and methodology
- Paper size standards (ISO 216 A-series): proportional scaling principles used in pattern drafting and graphic design.
- US paper sizes: ANSI/ASME Y14.1 American National Standard for Drawing Sheet Size and Format.
Reviewed by the CalculatorHub team, edited by James Graham, 14 June 2026. Scaling calculations are exact; tiling page counts assume no overlap margin. Add overlap in your print settings for alignment. See our methodology.