Design File Formatting

Print File Terminology

Let’s lay the foundation here and get into some terminology. It’ll help you get a better grasp of the rest of this blog and Viralstyle’s print file guidelines.

• Print size is the actual size of the image as it’ll come out printed on the product. It’s measured in inches or centimeters.

• Image file size is measured in bytes. It tells you how much space the image takes up on a disk or drive. For example, the maximum file size of an image you can upload on Printful’s Design Maker is 200 MB.

• A pixel is a unit of measurement for digital images you see on a screen.

• Pixel dimensions express the total number of pixels along a digital image’s width (vertical) and height (horizontal).

• Resolution expresses the density of pixels or dots in an image. For digital images, resolution is expressed in PPI—pixels per inch. For printed images, resolution is expressed in DPI—dots per inch.

• DPI (dots per inch) is a printing term. Digital devices display images in pixels, and printers print images in dots. DPI is calculated using your digital image’s pixel dimensions and digital image size.
The higher the DPI = the more the dots = the sharper the print.
The lower the DPI = the fewer the dots = the blurrier the print.

To help you visualize the relation between dimensions and resolution, look at the 3 penguins below. The images have the same dimensions (width and height), but they have different resolutions (DPI).

So, which of these looks the best?

Onto the make-or-break guidelines.

File Type

We always recommend uploading high-quality .PNG files to the designer tool. Always make sure your designs have a transparent background too. We also accept .JPG and .EPS files.

Artwork Dimensions

Although artwork dimensions are important, it’s image resolution you really want to pay attention to. We recommend creating designs with 300 DPI (dots per inch) whenever possible. The higher the DPI the higher resolution or quality of your image.

  • Maximum size of the print area: depends on the product you choose (e.g. the standard print area for t-shirts is 12″ × 16″, but for 11 oz. mugs—9″ × 3.5″).
  • Print file resolution (DPI): again, depends on the product but should be at least 150 DPI, and no higher than 300—going beyond 300 DPI won’t improve the print quality, just increase file size.
  • Print files for smaller items, like mugs, or personalized phone cases, need a DPI higher than 150 because those prints are small and often detailed. We recommend submitting designs for these products with a DPI of 300.

For more information about individual product dimension requirements, see our knowledge base.


Text size is also another common pitfall among designs. If it’s too small, it will appear illegible and unclear in the printing process which will disappoint customers. 10 points (13 pixel) is the minimum acceptable text size. Here’s a technical tidbit to experiment within the photo editor, before exporting your design turn off the ‘anti-aliasing’ feature to improve clarity around the borders of the image.

Color Scheme

As far as color schemes, we recommend the RGB color wheel for your designs. The CMYK color wheel is also another option if you prioritize color accuracy and vibrancy. Avoid using JPEG images, stick to PNG format images with a transparent background for best possible image resolution with a maximum 50MB file size.

Why sRGB and not CMYK?

sRGB has a wider, more vibrant color range (aka gamut) compared to CMYK.

Our DTG printers work with an upgraded CMYK color space where we’ve added more ink colors, allowing us to achieve print colors that normally fall outside of the CMYK color range. The closest color space to our upgraded CMYK is the sRGB IEC61966-2.1 and that’s why we recommend it for print files.

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