Graphics can be created in a raster or vector format. We can print from both formats just as well but the end result could vary slightly. Most images you view online are in a jpeg, gif, or PNG format online. These are raster images and contain pixels. Zooming in to a picture online you start to see all the square pixels and the image looks very pixilated. When you try to increase the size of these graphics the pixels expand and become more visible so we try to keep all raster images at 300 PPI or greater to have a high quality print. 72 PPI would be the lowest you want your artwork to be and would get you an acceptable quality print.
Depending on viewing distance, you may not need that much resolution but here's a quick chart on how much resolution is needed for how far away the viewer is (assuming 20/20 vision):
6" 600 PPI (vector would be best)
12" 300 PPI
24" 150 PPI
48" 75 PPI
And this will also depend the following:
- How small the details are
- How much actual resolution is within the image (not blurry or resized—must be the original design/image)
- Lighting and viewing conditions (different temperature lights, intensity, outdoor/atmospheric changes such as fog, smoke, rain, etc.)
For the best result we recommend vector format. Vector files are typically what the original artist created and contain no pixels at all! They are usually a .eps, .AI, .SVG and sometimes even .PDF(but not always). Vector graphics are scalable to any size as they retain data on the exact curve and shape so they will look perfect and the same at 1 inch or 10 feet! Not all designs can be vector format (such as photographs or extremely detailed paintings/illustrations) but most can so if you need help getting your artwork in vector format let us know and we can get it recreated for a small charge depending on the level of detail and give you a copy for your records as that is the type of file you need to make shirts, hats and most other quality merchandise.