This is a number telling a device (in our case a printer, but could be a computer screen) how many pixels (dots) in the image to fit within a physical measurement – usually an inch (dpi) but sometimes a centimetre (dpcm).

For example, if you have a 3000 pixels square image and you set the resolution to 300dpi (dots per inch), your image will print to 10 x 10 inches (3000 / 300 = 10).

Dots Per Inch. This is the common measurement of resolution for printed items, the most common DPI for print is 300dpi, this means that when an image is printed with a resolution of 300dpi, there are 300 dots within an inch (25mm) of the printed image. No one seems to know where 300dpi comes from – as a standard for print – we actually print to 360dpi because it produces a much sharper image with the printers we use.

Pixels Per Inch, this is a fairly modern term which has come from device screen resolutions, previously all screens were 72ppi, but with smart phones, tablets and now computer and laptop screens being produced to high resolutions (retina from Apple for example), this term has become common place.

This is actually a lot more important than the resolution setting of your image. Most digital cameras for example will by default save images at 72dpi, with this setting the print size of images will appear a lot larger than what is actually possible with the image. A 3000 x 2400 pixel image with a resolution of 72dpi will have a document / print size of about 41.6 x 33.3in (1058 x 847mm) – but if we printed an image at 72dpi the quality would be very poor and you would see pixelation throughout the print – the same 3000 x 2400 pixel image with a resolution of 360dpi will have a document / print size of 8.3 x 6.6in (210 x 167mm). Here’s a guide to ideal and minimum pixel sizes for some popular print measurements.

Printed Area Size |
180dpi (minimum) | 360dpi (ideal) |

ACEO 2.5 x 3.5in (63 x 89mm) |
450 x 630 | 900 x 1260 |

7 x 5in (127 x 178mm) |
1260 x 900 | 2520 x 1800 |

A5 (210 x 148mm) |
1490 x 1050 | 2976 x 2105 |

8 x 8in (200 x 200mm) |
1440 x 1440 | 2880 x 2880 |

10 x 8in (250 x 200mm) |
1800 x 1440 | 3600 x 2880 |

12 x 8in (300 x 200mm) |
2160 x 1440 | 4320 x 2880 |

A4 (297 x 210mm) |
2105 x 1490 | 4209 x 2976 |

14 x 11in (355 x 280mm) |
2520 x 1980 | 5040 x 3960 |

12 x 12in (305 x 305mm) |
2160 x 2160 | 4320 x 4320 |

16 x 12in (406 x 305mm) |
2880 x 2160 | 5760 x 4320 |

A3 (420 x 297mm) |
2977 x 2105 | 5953 x 4209 |

16 x 16in (406 x 406mm) |
2880 x 2880 | 5760 x 5760 |

20 x 16in (508 x 406mm) |
3600 x 2880 | 7200 x 5760 |

A2 (594 x 420mm) |
4210 x 2977 | 8419 x 5953 |

24 x 16in (610 x 406mm) |
4320 x 2880 | 8640 x 5760 |

20 x 20in (508 x 508mm) |
3600 x 3600 | 7200 x 7200 |

700 x 500mm (Poster) |
4961 x 3544 | 9921 x 7087 |

20 x 30in (508 x 762mm) |
3600 x 5400 | 7200 x 10800 |

A1 (840 x 594mm) |
5940 x 4212 | 11906 x 8419 |

24 x 36in (610 x 915mm) |
4320 x 6480 | 8640 x 12960 |

360dpi is the ideal resolution to print on our printers based on their own print head and nozzle set up. If you do have the option to work in, or you are able save/export your images to 360dpi, you will notice an improvement over the same image printed at 300dpi.