Paper size calculation
A4 pixels at 300 DPI
A4 measures 210 × 297 mm, or approximately 8.27 × 11.69 inches.
The calculation
Convert millimetres to inches by dividing by 25.4, then multiply by the target DPI. Rounding to whole pixels gives 2,480 × 3,508 at 300 DPI.
Add bleed separately
If a printer requests 3 mm bleed on each side, the exported page is 216 × 303 mm before conversion. Do not confuse the bleed size with the final trimmed A4 size.
A4 is not US Letter
US Letter is wider and shorter. Sending A4 content to a Letter workflow can introduce scaling or larger margins.