What resolution and format do you need for printing?
By Nasir Uddin Shamim · Founder, PrintxPDF
Updated 2026-08-26 · 8 min read
Short answer: For anything held in the hand, supply 300 pixels per inch of final print size: 2480 × 3508 px for A4, 2550 × 3300 px for US Letter, 1200 × 1800 px for a 4 × 6 photo. Posters viewed from a metre away are fine at 150 DPI. Upscaling invents pixels and does not add real detail.
The number that matters is not the file size or the megapixel count. It is pixels divided by inches: how many pixels land in each inch of the finished print. Everything else follows from that one ratio.
Where 300 DPI comes from
It is not a marketing number. Commercial offset printing screens images at around 150 lines per inch, and the long-standing rule in prepress is to supply image data at twice the line screen. 150 × 2 = 300. Below that you start to see the halftone structure; above it the press simply cannot resolve the extra detail, so the file gets bigger for nothing.
Home inkjets advertise much larger numbers, like 4800 × 1200 dpi, but those describe ink droplets, not image pixels. It takes many droplets to reproduce one pixel of continuous tone. Feeding an inkjet a 1200 PPI image gains you nothing over 300.
Pixel dimensions by paper size
| Print size | At 150 DPI (draft) | At 300 DPI (final) | Megapixels at 300 |
|---|---|---|---|
| 4 × 6 in photo | 600 × 900 | 1200 × 1800 | 2.2 MP |
| 5 × 7 in photo | 750 × 1050 | 1500 × 2100 | 3.2 MP |
| 8 × 10 in photo | 1200 × 1500 | 2400 × 3000 | 7.2 MP |
| A5 (148 × 210 mm) | 874 × 1240 | 1748 × 2480 | 4.3 MP |
| A4 (210 × 297 mm) | 1240 × 1754 | 2480 × 3508 | 8.7 MP |
| US Letter (8.5 × 11 in) | 1275 × 1650 | 2550 × 3300 | 8.4 MP |
| A3 (297 × 420 mm) | 1754 × 2480 | 3508 × 4961 | 17.4 MP |
| 13 × 19 in poster | 1950 × 2850 | 3900 × 5700 | 22.2 MP |
Minimum pixel dimensions for common print sizes.
To check any image yourself, divide its pixel width by the width you want to print in inches. A 3000-pixel-wide photo printed 10 inches wide is 300 DPI. The same photo printed 20 inches wide is 150 DPI. Nothing about the file changed; only the size you asked for did.
Viewing distance changes the answer
The 300 DPI rule assumes normal reading distance, roughly 30 cm. Human vision resolves about one arcminute, so the further away something is viewed, the coarser it can be without anyone noticing. This is why billboards printed at 15 DPI look perfectly sharp from the road.
| Piece | Typical viewing distance | Practical resolution |
|---|---|---|
| Business card, book, brochure | 30 cm | 300 DPI |
| Wall poster, exhibition print | 1 to 2 m | 150 DPI |
| Trade-show banner | 2 to 4 m | 100 DPI |
| Building wrap, billboard | 10 m or more | 15 to 30 DPI |
CMYK and RGB
Screens emit light and mix red, green and blue. Presses lay ink on paper that reflects it. The two gamuts overlap but are not the same shape, so some colours you see on screen, saturated oranges, vivid cyans, electric blues, cannot be reproduced with process inks. They are converted to the nearest printable colour, which usually reads as duller.
- Home and office printing: send RGB. Your printer driver handles the conversion and is tuned for its own inks. Converting to CMYK yourself first usually makes things worse.
- Commercial offset printing: ask the printer what they want. Many modern workflows now prefer RGB with an embedded profile and do the conversion themselves; others want files already in their specific CMYK profile.
- sRGB is the safe default for anything shared or uploaded. Adobe RGB holds more saturated colours but is misread as dull by software that ignores profiles.
- Rich black: pure K-only black prints as a slightly washed dark grey on large areas. Print shops typically use a rich black around 60C 40M 40Y 100K for solid backgrounds, while keeping small body text 100K only so it stays sharp.
Note: Black text should always be one ink. Text set in a four-colour black shows coloured fringes if the press is even slightly out of registration. This is one of the most common reasons a printed proof looks blurry when the file looked perfect.
Which format to send
| Format | Use it for | Watch out for |
|---|---|---|
| Complete documents, anything with text | Embed all fonts. PDF/X-1a or PDF/X-4 for commercial work. | |
| TIFF | High-quality photos, scans for reproduction | Very large files. Use LZW compression. |
| PNG | Logos, screenshots, graphics with transparency | RGB only; no CMYK support at all. |
| JPG | Photographs, when size matters | Export at quality 90 or above. Never re-save repeatedly. |
| SVG / AI / EPS | Logos, line art, anything scaled large | Vector: resolution-independent, so DPI does not apply. |
For a document rather than a single image, PDF beats all of them. It carries text as text, so type prints at the printer’s full resolution rather than at whatever DPI you rasterised to. That is why saving a web page as a PDF prints far more crisply than screenshotting it.
The upscaling myth
Enlarging an image in Photoshop or any other editor does not recover detail. Traditional interpolation, bicubic, Lanczos, examines neighbouring pixels and guesses the values in between. The result has more pixels and exactly the same amount of real information, spread thinner. A 600 × 400 photo resampled to 3000 × 2000 is a soft 600 × 400 photo with a bigger file size.
Modern AI upscalers are better at this and can produce a convincing 2× enlargement. But they invent plausible detail from a trained model rather than recovering what was there, fine for a decorative background, a serious problem for a product photo or a document scan.
Watch out: Never upscale text or a scanned document to hit a DPI target. Rescan it at the correct resolution instead. Upscaled type looks visibly soft on paper and wrecks OCR accuracy, because the character shapes have been smeared by interpolation.
A pre-print checklist
- Divide pixel width by intended print width in inches. Aim for 300, accept 200, worry below 150.
- Check the real viewing distance before insisting on 300 for a large piece.
- Add 3 mm of bleed on every edge if any colour runs to the edge of the paper.
- Keep important content at least 5 mm inside the trim line.
- Set body text to black ink only, not a four-colour mix.
- Embed every font, or convert type to outlines.
- Print one page at actual size on your own printer before ordering five hundred.
Need a page as a print-ready image? Render it at 300 DPI rather than screenshotting the screen.
If your finished file is now enormous, that is normal for print resolution, but do not compress it before the printer sees it. Compression is for email and archives, not for the press.
Frequently asked questions
How many pixels do I need to print an A4 page?
A4 at 300 DPI is 2480 × 3508 pixels, about 8.7 megapixels. At 150 DPI, acceptable for drafts and internal copies, it is 1240 × 1754 pixels. Below roughly 150 DPI the softness becomes obvious at reading distance.
Is 300 DPI always necessary?
No. 300 DPI assumes the piece is held at reading distance. A poster viewed from a metre away looks sharp at 150 DPI, a trade-show banner at 100, and a billboard at 15 to 30. Match the resolution to the viewing distance.
Should I convert my images to CMYK before printing?
For home and office printers, no, send RGB and let the driver convert. For commercial offset printing, ask the printer: many now prefer RGB with an embedded profile, while others require a specific CMYK profile.
Can I make a low-resolution image printable by upscaling it?
Not really. Interpolation adds pixels without adding information, and AI upscalers invent plausible detail rather than recovering the original. Both are acceptable for decorative images and unsuitable for documents, product photos or evidence.
What is the difference between DPI and PPI?
PPI describes pixels in a digital image; DPI describes ink dots a printer lays down. They are used interchangeably in everyday practice, but a 4800 dpi inkjet still only needs a 300 PPI image, because many dots make up one pixel.