Bleed size calculator
Add the same bleed beyond every trim edge, then translate the full document size into pixels.
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Bleed is added twice on each axis
The document extends past both the left and right trim edges, and past both the top and bottom edges. A 0.125-inch bleed therefore adds 0.25 inches to width and height.
Use the printer’s specification
The default is only an example. Required bleed, safe area, crop marks and export settings vary by printer and product; their production specification is authoritative.