Both JPG and PNG convert to PDF in one click, so the choice is not about what works — it is about what you get: the size of the finished PDF, how sharp text and edges look, and whether transparency survives. The short answer is JPG for photos, PNG for screenshots and graphics. The rest of this guide explains why, and what each format does to your file on the way in.
What the two formats actually do
JPG (JPEG) is lossy. When a camera or app saves a JPG it throws away detail the eye is unlikely to notice — mostly fine colour variation — in exchange for a much smaller file. That trade is excellent for photographs, where there is no such thing as a perfectly sharp edge, and poor for text and line art, where the discarded detail shows up as faint smudges around letters.
PNG is lossless. Every pixel is stored exactly, which keeps screenshots, logos, and rendered text perfectly crisp. The cost is size: PNG compresses flat areas of colour extremely well and photographs extremely badly. PNG also supports transparency; JPG does not.
Side-by-side
| JPG to PDF | PNG to PDF | |
|---|---|---|
| Best for | Photos, camera scans of paper | Screenshots, text from a screen, logos, diagrams |
| Compression | Lossy (already applied when the JPG was saved) | Lossless |
| Typical size for a 12 MP photo | 3–6 MB | 20–40 MB |
| Typical size for a full-screen screenshot | 0.3–1 MB, with smudged text | 0.2–2 MB, text perfectly sharp |
| Transparency | Not supported (background is baked in) | Preserved; shows as white on the page |
| What this converter does | Embeds the JPEG bytes as-is; no recompression | Embeds the PNG losslessly |
| Tool | JPG to PDF | PNG to PDF |
Choose JPG when…
- The source is a photograph. Receipts, ID cards, and documents photographed with a phone are already JPG (or HEIC, which Safari hands over as JPEG). The detail JPG discards is invisible on a printed page.
- File size matters. A 10-page document photographed on a phone comes out at 30–50 MB as JPG; the same pages as PNG would be several hundred megabytes, and email attachment limits are usually 20–25 MB.
- You already have JPGs. Converting a JPG to PNG first gains nothing — the quality loss has already happened — and makes the PDF much bigger.
Choose PNG when…
- The image contains rendered text. Screenshots of a web page, a chat, an error message, or a spreadsheet stay perfectly legible as PNG. As JPG, small text gets a halo of compression artefacts.
- Edges must stay clean. Logos, icons, charts, and diagrams have hard edges and flat colours, exactly the content PNG compresses well and JPG smears.
- The image is transparent. A logo with a transparent background keeps it in the PDF (it will display over the white page). Saved as JPG, the transparent area becomes a solid colour.
What about scanned paper?
A scan from a flatbed or office scanner is a photograph of paper, and JPG at high quality is the sensible choice: the text is large enough that JPG artefacts do not affect legibility, and the file stays small. If the scanner offers PNG or TIFF, use it only when the document has very fine print or you need an archival copy. Multi-page TIFF files convert directly with the TIFF to PDF tool, one page per PDF page. For the full workflow see how to combine scanned documents into one PDF.
What this converter does to your image
The answer is: as little as possible. A JPG is written into the PDF as the same JPEG data that was in the file — it is not decoded and re-saved, so no second round of compression happens. A PNG is embedded losslessly, alpha channel included. Each image is placed on a US Letter page: larger images are scaled to fit inside a small margin, smaller ones are centred at their natural size, and in both cases the pixel data is unchanged. Up to 20 images go into one PDF per batch, each up to 200 MB, and the conversion runs inside your browser so the images are never uploaded.
A quick rule of thumb
If the image came from a camera, convert it as JPG. If it came from a screen or a design tool, convert it as PNG. If it is a vector file, use SVG to PDF instead of exporting a raster at all.