You print. The printer hums. The page comes out and your document is a postage stamp in the top-left corner.
This is a print-size mismatch. The PDF and the paper aren't talking to each other.
What's actually going wrong
PDFs have an internal page size. If your file's pages are 8 inches square but your paper is A4, the print driver doesn't know what to do — it defaults to printing at original size, leaving you with a tiny block on a big sheet.
This happens most often with PDFs exported from web pages, mobile screenshots, or apps that default to non-standard page sizes.
The quick fix
In your print dialog, look for 'Page Sizing' or 'Page Scaling' and set it to Fit or Fit to printable area. The printer will scale the content up to fill the page. That solves it for one print job.
For a permanent fix, rebuild the PDF with correct page sizing. Convert to Word, open in Word, set page size to A4 or Letter, then convert back to PDF. The file is now standard-sized and prints at full scale by default everywhere.
If that didn't work
If 'Fit to page' produces a print that's still small, the actual content is small within the PDF — the file has correct A4 pages with tiny content laid out in the corner. In that case, use convert PDF to JPG to extract the content as an image, crop in any image tool, then convert image to PDF with proper sizing.
For multi-page documents with this problem, do it once per page and merge the PDFs back together.
Prevent it next time
Always set page size at export. In Word, Pages, Google Docs — make sure the document is A4 or Letter before exporting to PDF. For screenshots and web captures, use a tool that exports at standard sizes by default.
FAQ
What does 'fit to page' actually do?
It scales the PDF content proportionally up or down so the largest dimension fills the printable area of your paper. It's a print-time fix that doesn't change the file.
Why does my A4 PDF print at letter size?
Your printer is forcing the closest standard size. Set the paper size in the print dialog explicitly to A4, or change your printer default. The PDF itself is fine.
Can I resize a PDF's pages?
Indirectly. Convert to Word, change page size, convert back. Direct page resizing isn't a standard PDF operation because content positioning depends on the page dimensions.
Why is my receipt PDF so tiny when printed?
Receipts are typically 80mm-wide PDFs. On A4 paper that's a thin strip. Either print 'fit to page' for a giant receipt, or change the source app's PDF export setting to A4.
Tiny prints are a sizing mismatch, not a broken file. Fix the scale once in Flint and your PDFs print at full size every time.