The sizes at a glance
A4 measures 210 × 297 mm. US Letter measures 8.5 × 11 inches (215.9 × 279.4 mm). A4 is narrower and taller. They are close in size, but they are not interchangeable at 100% scale.
Use the matching edition
If a pack includes both sizes, select the PDF that matches your paper and choose that size in the print dialog. Not every product includes both sizes; check the product and current Etsy listing before buying.
When the pack has only one size
A PDF reader can often scale a page to fit another paper size, but that can shrink artwork, move margins, or change craft dimensions. For puzzles, templates, and gifts that need to align, use the intended paper and test one page before assembly.
