Guide
Converting between A4, Letter and other paper sizes
Most of the world uses A4 paper (210 × 297 mm). The United States, Canada and parts of Latin America use US Letter (8.5 × 11 in, or 216 × 279 mm). The two look alike but are not the same: Letter is 6 mm wider and 18 mm shorter. Send a Letter document to someone in Europe or India and their printer either shrinks it, crops the bottom, or stops to ask for paper that isn’t loaded. Converting the PDF to the right size before sending avoids all three.
What resizing actually does
A PDF page has a fixed size. Resizing creates a new page of the chosen size and places the original content on it:
- Scale to fit, keep proportions shrinks or enlarges the content by the same amount in both directions until it fits, and centres it. Nothing is stretched or cut.
- Keep its size, centered leaves the content at 100% and only changes the paper around it. Content larger than the new page is cut off.
Text is not re-flowed: lines keep their breaks, and a page stays a page. That’s what makes resizing safe for contracts and forms, where the layout must not change.
Choosing settings for common conversions
- Letter → A4: scale to fit. The content shrinks by about 3% and a thin band appears at the top and bottom. Nobody will notice.
- A4 → Letter: scale to fit. The content shrinks by about 6% to fit the shorter page, with thin bands at the sides.
- A3 drawings → A4: scale to fit; everything becomes 71% of its size. Check that small labels are still legible.
- A5 booklet pages → A4: scale to fit with enlarging on, so they fill the A4 sheet.
- Scans with uneven sizes: choose A4 or Letter and the whole file becomes uniform, which also helps before merging.
Orientation
Leave orientation on Same as each page for most documents: a landscape spreadsheet page becomes a landscape A4 page instead of being squeezed into portrait. Force All portrait only when the pages will be bound and must all face the same way.
Margins for printing
Many printers cannot print the outer 3 to 5 mm of a sheet. If the content reaches the edges, add a white margin of 5 to 10 mm; the content is scaled to fit inside it. For margins on chosen sides, or a binding gutter, use Add PDF Margins instead.
What the original keeps and loses
Pages are placed as vector content, so text stays sharp and selectable and the file stays small. Rotated pages are handled as a reader shows them. Clickable links, the bookmark sidebar and fillable fields belong to the old pages and are not carried over; keep the original if you need them.
A worked example
An Indian consultant receives a 40-page US proposal to print locally.
- Open the PDF; the summary reads 40 × Letter portrait.
- Choose A4, keep orientation and Scale to fit.
- Download, print at 100%, and nothing is cut off at the bottom.
To trim existing white space before resizing, use Crop PDF. To print several pages on one sheet, see N-Up PDF, and for one page across several sheets, PDF Poster Maker.
Checked against the current version of the Change PDF Page Size on .