Paper sizes and custom sheets

The sheet is the paper going through the machine. It is set independently of your page size, and everything else in the imposition — the grid, the gaps, the margin the crop marks need — is solved inside it. Six formats are built in; everything else is Custom.

Custom sheets

Choose Custom and give an explicit width and height. There is no list to pick from and no preset beyond the six above, which means anything oversized, anything metric-but-not-ISO, and every house sheet your shop keeps is set the same way: by typing the two numbers.

SRA3, the worked example

SRA3 is the obvious case, because it is the standard sheet for short-run digital work and it is not a preset. It is 320 × 450 mm — the oversized relation of A3, with the extra 23 mm across and 30 mm down existing precisely so an A3 finished piece can bleed and still be trimmed.

Set Custom, enter 320 and 450, and impose as normal. That extra area is what makes SRA3 worth using: an A3 page centred on an SRA3 sheet has 11.5 mm of clear paper at each side and 15 mm top and bottom, which comfortably holds a 3 mm bleed and the 8 mm the crop marks need. The same page on a true A3 sheet has nothing at all.

Choosing a sheet

Work outward from the finished piece and the constraints arrive in this order:

1. Start with the trim size of the piece, plus the bleed on all four sides. A 3 mm bleed adds 6 mm in each axis.
2. Add the gutters between pieces. A shared cut between two bleeding pieces needs twice the bleed — see bleed and gutters.
3. Add 8 mm of clear sheet at every outside edge for the crop marks: 3 mm of distance plus a 5 mm mark. That is 16 mm off each sheet dimension before anything is placed.
4. Whatever is left is what you have to fit the grid into. If the answer is a fraction of a piece, you lose that row or column, or you reduce the scale.

On A3 that leaves a usable 281 × 404 mm. On SRA3 it leaves 304 × 434 mm — one more column of business cards, most of the time, which is the whole argument for the larger sheet.

Orientation

The sheet dimensions are stated width first. If you need the sheet the other way round, set a Custom size with the numbers swapped — 420 × 297 rather than A3, for instance. Rotating the pages is a different control and does not turn the sheet; see page ranges, rotation and scale.