DPI (dots per inch) measures pixel density. For print, 300 DPI at the intended print size is the standard minimum. A 72 DPI image designed for screens will look blurry in print.

The critical mistake: resizing a low-resolution image to a higher DPI in Photoshop doesn't create new detail. It just interpolates (guesses) what the missing pixels should be. The result is a blurry, smeared print.

How to check: in Photoshop or Preview, check "Image Size" with "Resample" turned OFF. Change the resolution field to 300 DPI and look at the print dimensions. If the dimensions drop below your intended size, the file is too low-res.

For a standard front chest print (~12" wide), you need an image that is at minimum 3,600px wide (12" × 300 DPI = 3,600px). For a full front design (~14" wide), that's 4,200px.

Social media graphics are typically 72–96 DPI and sized for screens. They are almost never print-ready without a complete redesign.