The formula behind a print-size calculation
Convert to inches first
Pixels equal physical inches multiplied by pixels per inch. Centimeters are divided by 2.54 before applying that formula.
Work on both edges
Calculate width and height separately and preserve the intended proportions. A 10 × 12 inch design at 300 PPI requires 3000 × 3600 pixels.
Distinguish required pixels from source quality
The calculation describes a target grid. Enlarging a low-detail image to that grid will not create the missing detail. Check the source artwork and the provider’s specifications before exporting.
Try the workflow
10 inches at 300 pixels per inch needs 3000 pixels on that edge. A 5000-pixel edge at 300 PPI represents about 16.67 inches.
Open print size and dpi calculator