Comparing Dots Per Inch and Pixels Per Inch

Quality photographs for print or online are often a frustration for small business owners. A photo that looks great on an illuminated computer screen may not be suitable for print materials. Let's compare a photo business card design for print as one example with advice comparing dots per inch (dpi) and pixels per inch (ppi).

Standard US card widths are 3 inches. The preferred camera resolution is 300 dpi for print. At 72 dpi a photo will look great in a website design, but cannot be used for print. Graphic artists will usually tell clients they need a 300 dpi resolution photo, or better. Print shops think in terms of lines per inch or pixels per inch, and again, 300 ppi, or better is necessary. High end printing may require 1200 ppi.

To calculate the resolution of a photograph for a 3 inch wide business card, view the dimensions under the size column in My Documents for the photo you intend to use. Divide the card width in pixels by 3 (for the 3 inch width of the card) to see if you hit the magic number. A 300 pixel wide photo divided by 3 yields 100 pixels per inch, so at 100 ppi it would have to be enlarged to fit the card, and at 100 ppi it is not suitable. The enlarged version would be blurry when printed.

This same calculation works for larger print projects, also. For a 6 inch wide post card you can reverse the math to figure you need 6 x 300, or an 1800 pixel wide photo. That same 300 pixel wide photo that looks great on a computer screen would yield 50 ppi for our 6 x 4 post card flyer test.

So despite requests by your graphic artist for 300 dpi photos for print, a 300 dpi postage stamp size photo just won't work on a highway billboard sign, let alone a small post card. A bigger photograph is always better when designing printed marketing materials.



TAGS: advice business card design graphic artwork photographs small business advice