JPG, PNG or PDF: which format for scanned documents?
Published September 1, 2026 · Updated September 26, 2026
Every scan ends with the same question: which format do I save it in? The honest answer is that each of the three common choices is best at something specific, and picking well takes about ten seconds once you know the trade-offs. Here is what each format actually does, some realistic size numbers, and a cheat sheet for the situations that come up most.
JPG: small and everywhere
JPG compresses aggressively, so a scanned page is typically a few hundred kilobytes. For text documents at reasonable quality settings the compression artifacts are invisible in practice. Use JPG when file size matters — email attachments, uploads with size limits, archives of hundreds of receipts. Its one real weakness: recompressing it repeatedly (edit, save, edit, save) slowly degrades the text edges.
PNG: exact but heavy
PNG is lossless: what the scanner produced is exactly what the file holds, at the cost of files several times larger than JPG. Choose PNG when the scan will be edited again, when fine detail matters (small print, technical drawings, stamps and seals), or when a single page needs to look perfect on screen.
PDF: the format for sending
PDF is not an image format but a container — which is exactly why it wins for anything multi-page or anything official. Page order is fixed, printing is predictable, and recipients expect it. The pattern that serves most people: PNG or JPG for single pages you keep, PDF for anything you send or anything longer than one page. Scandut saves all three, so the choice costs one click either way.
Realistic size numbers
An A4 text page scanned around 2000 pixels wide lands roughly here: JPG at standard quality, 300–600 KB; the same page as PNG, 2–5 MB; a ten-page PDF built from JPG pages, 3–6 MB at standard quality and two to three times that at high quality. Grayscale (B&W mode) shaves another 30–50% off. These numbers vary with content — dense diagrams compress worse than clean text — but they are close enough to plan with: a 25 MB email limit fits a 40–60 page standard-quality PDF.
Cheat sheet
Sending a signed form to an office: PDF, A4 mode, standard quality. Archiving warranties and receipts: monthly PDF, or JPG files named by date. A diagram you will annotate later: PNG. A contract you may need to print: PDF at high quality. Text you need to quote or edit: run OCR and save TXT or DOCX next to the scan. Hundreds of book pages: PDF in batches per chapter, Document mode, standard quality.