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Before you set 600: is it the right number?
Most people who arrive here were told “300 DPI” and reached for the next number up. For a photograph, that is usually wasted: commercial presses screen at 150–175 lines per inch, and 300 pixels per inch is already the conventional double of that. Going to 600 asks your file to claim half the physical size, so unless you also have four times the pixels, the practical effect is a smaller print, not a better one.
There are jobs where 600 is genuinely correct, and they have something in common — hard edges rather than continuous tone:
- Line art, logos and technical drawings. A stepped diagonal edge is visible at 300 and disappears at 600.
- Scanned text and documents, especially anything going through OCR — most engines read small type more reliably from 600 DPI scans.
- Engraving, laser cutting and die lines, where the machine follows the edge itself.
- Fine-art and giclée printing on some presses, where the shop asks for 600 explicitly.
- Newsprint and stamp-sized reproduction of detailed artwork, where the printed area is tiny and the detail is fine.
If your job is not on that list and your printer did not ask for 600 by name, 300 DPI is the safer answer.
How many pixels 600 DPI needs
Four times as many as 300 for the same paper, because the requirement is squared in both directions.
| Printed size | Millimetres | Pixels needed at 600 DPI |
|---|---|---|
| A4 | 210 × 297 | 4961 × 7016 |
| A5 | 148 × 210 | 3496 × 4961 |
| US Letter | 216 × 279 | 5100 × 6600 |
| Photo 10 × 15 cm | 100 × 150 | 2362 × 3543 |
| Business card | 85 × 55 | 2008 × 1299 |
A 12-megapixel phone photo (about 4000 × 3000) does not cover A4 at 600 DPI. It covers roughly 17 × 12.7 cm. That is the arithmetic behind most “600 DPI” requests that end in disappointment, and the panel below shows it for your specific file before you commit.
What happens to the file
The density field is rewritten and every other byte is copied through. No re-encode: a JPEG loses no further quality, a PNG stays byte-identical in its image data. For JPEGs the value is written to both the JFIF header and the EXIF resolution tags, so software that prefers EXIF — Photoshop, InDesign, most prepress tools — reads the same number as everything else.
The work happens in your browser. No file, and no fact about a file, is transmitted.
How to convert an image to 600 DPI
600 is already selected below; you only need to supply the file.
Step 1: Add your JPG or PNG
Drag it onto the box above or click to browse. A batch is fine — multiple files come back as a ZIP.
Step 2: Check the print size it reports
The panel shows what the file declares now, its pixel dimensions, and the physical size it will print at 600 DPI. This is the moment to notice that 600 wants four times the pixels of 300.
Step 3: Convert and download
Press the button. The rewritten file downloads with a `_600dpi` suffix; the original on your disk is untouched.
Frequently Asked Questions
Is 600 DPI better than 300 DPI?
Only for the right material. For line art, scans and engraving, yes. For a photograph on a commercial press, 300 already exceeds what the screen can reproduce, and 600 mostly buys a larger file and a smaller print.
Can I turn a 300 DPI file into a real 600 DPI file?
Not by re-tagging. Genuine 600 DPI output needs four times the pixels, which means re-scanning at 600, re-exporting from the vector original, or re-shooting. Anything else is resampling — inventing pixels — and it shows on hard edges, which is exactly where 600 matters.
Why does my scanner say 600 but the file says 72?
Some scanning software captures at 600 and then writes a web default into the exported file, or the density is lost in a later export. The pixels are the evidence: if the pixel count matches a 600 DPI scan of that original, the capture was fine and only the tag needs correcting.
Does 600 DPI make the file bigger?
Not here. Changing the tag adds a handful of bytes at most, because no pixels are added. A file that is genuinely captured at 600 is large, but that is the capture, not the label.
Related Tools
- Convert an Image to 300 DPIRe-tag a JPG or PNG as 300 DPI without touching a single pixel — and see, before you send it, whether the file really covers the paper.
- Check the DPI of an ImageFind out what your file really declares — including the case where a JPEG declares two different values at once.
- Image DPI Converter (72 to 300 DPI)Set the DPI your print shop asked for, and see the size the file will actually print at.