JPG vs PNG for Documents: Which Format to Use (With Real Test Results)
JPG is built for photos, PNG for sharp edges. For pages full of text, our own test found PNG was both sharper and smaller -- here's why, and when JPG is still the right call.
The one difference that matters: lossy vs lossless
JPG (also written JPEG) uses lossy compression. It splits the picture into small blocks and throws away fine detail the eye is least likely to miss. On a photograph -- smooth skin tones, sky, foliage -- the loss is very hard to see, and the file becomes far smaller.
PNG uses lossless compression -- its W3C specification describes it as a format for lossless storage of images. Nothing is thrown away, so what you save is exactly what you get back.
The difference shows on sharp edges. The boundary between black text and white paper is exactly the kind of detail JPG simplifies, which leaves faint smudges and speckles (called artifacts) around letters. PNG keeps those edges perfectly clean.
Transparency: only PNG has it
PNG can store an alpha channel -- a transparency value for every pixel -- which is why logos, icons and signatures with see-through backgrounds are usually PNGs. JPG has no transparency at all: every pixel is a solid colour.
What we measured on a real document page
We created a one-page A4 letter -- a heading and six paragraphs of ordinary 11-point text -- and turned it into images with our own PDF to PNG and PDF to JPG tools, which render at 300 dpi (2481 x 3508 pixels).
The PNG was 645 KB. The JPG was 1.1 MB -- about 70% larger -- and it had lost detail: around 65,000 pixels around the letters changed noticeably compared with the exact PNG. Saved as a greyscale PNG, the same page was just 347 KB.
The reason is simple. A text page is mostly large areas of plain white with sharp black edges. Lossless PNG compression handles plain areas extremely efficiently, while JPG spends a lot of data trying to approximate every sharp edge -- and still doesn't get them exactly right.
| Saved as | File size | Exact copy of the page? |
|---|---|---|
| PNG (colour) | 645 KB | Yes - lossless |
| JPG (quality 75) | 1.1 MB (about 70% larger) | No - around 65,000 pixels around the letters changed noticeably |
| PNG (greyscale) | 347 KB | Yes - lossless |
Photos are the opposite
A photograph has almost no plain areas: every pixel differs slightly from its neighbours. Lossless PNG can't compress that kind of detail well, so a PNG of a camera photo is typically several times larger than a good-quality JPG of the same picture, and the extra detail PNG preserves is usually invisible. For photos, JPG is the right choice.
Which one to use
PNG for scanned text documents, screenshots, forms, charts, diagrams, and anything you'll need to read or zoom into later.
PNG for logos and graphics that need a transparent background.
JPG for photographs -- including a photo of a receipt or a whiteboard, where the camera image itself is already full of fine texture.
Already have a JPG? Converting it to PNG won't bring back the detail JPG discarded; it only makes the file bigger. Keep JPGs as JPGs.
Editing an image several times? Work in PNG. Every time a JPG is edited and saved again, it is compressed again and loses a little more detail.
| JPG | PNG | |
|---|---|---|
| Compression | Lossy - discards fine detail | Lossless - keeps every pixel |
| Transparent background | No | Yes |
| Text and sharp edges | Faint smudges (artifacts) around letters | Perfectly clean |
| File size for photos | Small | Several times larger |
| File size for text pages | Larger in our test | Smaller in our test |
| Editing and re-saving | Loses a little more detail each save | No loss |
| Best for | Photographs | Scans of text, screenshots, forms, charts, logos |
How our converters handle JPG and PNG
PDF to PNG renders every page at 300 dpi and saves it losslessly -- the best choice for pages with text, tables or line drawings.
PDF to JPG renders every page at 300 dpi and saves it as a standard-quality JPG (quality 75). That keeps photo-heavy pages compact, but as our test shows, text-heavy pages are often smaller and sharper as PNG.
JPG to PDF places your JPG files into the PDF exactly as uploaded -- byte for byte -- so there's no second round of compression and no extra quality loss.
PNG to PDF embeds your images without any lossy compression and keeps greyscale images in greyscale. Transparent areas are placed on a white background, the same as a logo printed on paper.
Every uploaded image and every result is deleted from our server as soon as your download is ready.