Guides · Calculator

Album pixel calculator

Enter the page size, the bleed and the PPI your lab asks for and it tells you how many pixels the file needs, and whether your camera can fill it.

How the sum works

When a lab talks about a “12 × 12” album it means the page. If you export by spread, the width doubles, and the file needs bleed added on every edge, so twice the bleed value in each direction. For a 30 × 30 cm page with 3 mm of bleed, the file measures 60.6 × 30.6 cm.

To go from centimetres to pixels, divide by 2.54 to get inches and multiply by the PPI: 60.6 ÷ 2.54 × 300 = 7157 pixels wide, and 30.6 ÷ 2.54 × 300 = 3614 high. That is exactly what the calculator does, rounding to the nearest pixel. It is the same sum Cajista uses to build the file.

If the lab wants one file per page, choose “Single page” and the width is not doubled. If it gives you sizes in inches, change the unit: the values you have already typed convert on their own, the bleed included.

What bleed to use

Your lab decides, not you. It is in their spec sheet or in the template you download, and 3 mm per edge is the most common value. If in doubt, ask before exporting: a wrong bleed means redoing the files. If your lab asks for no bleed, enter 0 and the calculator gives you the clean size. What bleed is and why it matters is covered in preparing an album for print.

And the resolution?

300 PPI is the reference value and what most labs ask for, but if your lab’s spec sheet gives another number, theirs wins. That is the resolution of the file: how many pixels per inch the spread you send carries.

The resolution of the photo is a different sum, and it is what the “Your camera” line gives: how many pixels of the original land on each inch of paper if that photo fills the whole file, uncropped. A 24 MP photo is 6000 pixels wide; spread over the 60.6 cm of a 30 × 30 spread, that is 251 PPI. The file still comes out at 300, because the rest is interpolated.

Between 200 PPI and the resolution you asked for, the difference does not show on paper, but there is no room left to crop. Below 200 it shows, and that is where Cajista warns you on the slot before exporting. How far each photo can be cropped is covered in the sizes and resolution guide.