# Print resolution (DPI)

URL: https://tnb-tech.com/en/glossary/print-resolution/

## What is print resolution (DPI)?

Print resolution, measured in DPI, is how many dots a press lays down per inch, and therefore how many pixels a file needs at its final size. Anything read at arm’s length is prepared at 300 dpi. A banner, a sign or a billboard is seen from metres away and needs far fewer dots. Vector logos and text have no resolution at all and stay sharp at any size.

**Example**

The arithmetic is one line: pixels = millimetres ÷ 25.4 × dpi. A business card at 85×55 mm and 300 dpi needs a file of 1004×650 pixels. A roll-up banner at 85×200 cm, built at full size and 120 dpi, needs 4016×9449 pixels. A 4×3 m billboard is read from 20 metres or more, so 25 dpi at final size is enough — that is 3937×2953 pixels, about what a phone camera produces. Build the artwork at 1:10 and the required dpi multiplies by ten: the same banner at scale needs 1200 dpi to come out the same.

**Why it matters for a business**

A logo pulled off a website is usually around 500 pixels wide. That is fine for an online ad and useless for a roll-up: stretched across 85 cm it works out under 15 dpi, and the edges break up as soon as someone stands close. The opposite mistake costs too — an 8,000-pixel photo on a billboard looks no better and produces a file the press handles slowly. A raster image cannot be enlarged: interpolation adds pixels, not detail. So for print we ask the photographer for the originals, and logos and headlines stay vector.

**How to improve it**

- Build artwork at final size; if you work to scale, put the scale in the file name.
- Ask the photographer for the original files, not the versions resized for the website.
- Keep logos and type as vectors, and rasterise only the effects that force it.
- Match dpi to viewing distance: 300 up close, 100–150 for posters and roll-ups, 20–40 for billboards.
- Check the file at 100% on screen, not at 25%.Files for banners, signs and billboards are prepared as part of advertising materials.

- Services: [Advertising materials](https://tnb-tech.com/en/services/advertising-materials/)
- Glossary: https://tnb-tech.com/en/glossary/