Every project is in one of two modes. They are a single either/or choice, and the question worth answering is not "what does each one do" but "which one do I want".
The short version: pick the mode that matches whatever is fixed. If the number of sheets is fixed, use grid mode. If the finished size is fixed, use size mode.
Grid mode — you choose the sheets, the poster size follows
Grid mode sets the layout size using a fixed number of papers.
Set 3 columns × 3 rows of A4 and you get whatever poster that adds up to. You are choosing the grid; the finished dimensions are the result.
Use it when the constraint is the paper:
- "I have nine sheets and that is all I have."
- "I want it exactly 2 × 3, because that is what fits my frame arrangement."
- "I want to print a quick test at 1 × 1 before committing."
Size mode — you choose the size, the sheet count follows
Size mode automatically adjusts the grid and paper count to match your desired print size.
Enter 36 × 24 in and Docuslice works out how many sheets of your chosen paper that needs.
Use it when the constraint is the finished object:
- The wall, the frame, or the space the poster has to fill.
- A sewing or woodworking pattern that must print at true scale.
- Anything where being one sheet off is fine but being the wrong size is not.
Preset sizes
You do not have to know the numbers. In size mode the poster size controls include a Template dropdown — it reads Custom until you pick something — holding 28 ready-made finished sizes. Choosing one fills in the width and height and switches the unit to the one that size is normally quoted in. Typing your own width or height, or changing the unit, puts the dropdown back to Custom. The rotate button beside the thumbnail swaps width and height and keeps the name.
These are poster sizes, not paper sizes. Picking A2 does not print on A2 — it asks for a poster the size of an A2 sheet, tiled across whatever paper you have loaded. The paper stays whatever you chose from Supported Paper Sizes, and the sheet count is still worked out the way the next section describes.
In the order the dropdown lists them:
| Preset | Finished size |
|---|---|
| A0 | 841 × 1189 mm |
| A1 | 594 × 841 mm |
| A1+ | 609 × 914 mm |
| A2 | 420 × 594 mm |
| A3 | 297 × 420 mm |
| A3+ | 13 × 19 in |
| Manila Paper (Whole) | 48 × 36 in |
| Manila Paper (Half) | 24 × 36 in |
| Cartolina | 22.5 × 28.5 in |
| Illustration Board (1/8) | 10 × 15 in |
| Illustration Board (1/4) | 15 × 20 in |
| Illustration Board (1/2) | 20 × 30 in |
| Illustration Board (Whole) | 30 × 40 in |
| Tabloid | 11 × 17 in |
| Ledger | 17 × 11 in |
| US Poster 16x20 | 16 × 20 in |
| US Poster 18x24 | 18 × 24 in |
| US Poster 20x30 | 20 × 30 in |
| US Poster 22x28 | 22 × 28 in |
| US Poster 24x36 | 24 × 36 in |
| US Poster 27x40 | 27 × 40 in |
| US Poster 36x48 | 36 × 48 in |
| ARCH A | 9 × 12 in |
| ARCH B | 12 × 18 in |
| ARCH C | 18 × 24 in |
| ARCH D | 24 × 36 in |
| ARCH E | 36 × 48 in |
| ARCH E1 | 30 × 42 in |
Grid mode has no equivalent — the dropdown is part of size mode only, because a preset is a pair of dimensions and grid mode does not take dimensions.
The part worth knowing: how the sheet count is worked out
This section is about size mode only. In grid mode you typed the sheet count yourself, so there is nothing to work out and nothing below applies — see Grid mode is what you see.
In size mode the count is computed against the usable area of each sheet, not the full sheet. The usable area is the paper minus the margins on both sides:
columns = ceil( poster width / (paper width - left margin - right margin) )
rows = ceil( poster height / (paper height - top margin - bottom margin) )Two consequences surprise people.
Raising the margin can add a whole row or column
A bigger margin shrinks the usable area of every sheet, so the same poster needs more of them. This is the exact trade-off described in Why Some of My Printed Pages Are Cropped — and the reason that article recommends 0.50 in rather than "as much as possible".
The count always rounds up
There is no partial sheet. A poster one millimetre wider than a whole number of sheets costs a full extra column. If your sheet count jumped by one for no visible reason, check whether your dimensions are just over a boundary — trimming a few millimetres off the poster can remove an entire column.
Exact multiples are handled correctly: a poster that comes to exactly 3 sheets wide uses 3, not 4.
Grid mode is what you see
In grid mode the sheet count is not calculated at all — it is the number you typed. Set 3 × 3 and you export exactly nine sheets, whatever the margin is. Raising the margin leaves a wider blank border on each sheet, so there is less room for the image, but it never adds a sheet and never changes the grid.
That is the practical reason to reach for grid mode: the layout on the canvas is the layout that comes out of the printer.
"Grid auto-adjusted for margins"
In the export preview you may see a note reading Grid auto-adjusted for margins. It appears in size mode only. Grid mode never shows it, because the count you set cannot disagree with the count you get.
In size mode it means the grid drawn on the canvas and the grid that will actually be exported are not the same. The canvas grid divides your poster by the full sheet size; the export divides it by the usable area. Once the margin is large enough, those two numbers disagree, and the export needs more sheets than the canvas outline suggests.
This is not a bug and nothing is wrong with your project. The exported sheet count is the correct one. If you would rather the two agreed, lower the margin — bearing in mind what a small margin costs you — or switch to grid mode, where the question does not arise.
Limits
Both modes are bounded, and the bounds are the reason a value you type may not stick.
Grid mode — sheets per axis
Columns and rows are each held between 1 and 20. At the maximum on both axes that is 20 × 20 = 400 sheets, which is the largest poster grid mode will build.
Size mode — finished poster dimensions
Width and height are each held between 1 and the maximum for the unit you are entering in. Switching the unit re-applies that unit's maximum.
| Unit | Maximum width or height |
|---|---|
| cm | 500 |
| ft | 20 |
| in | 200 |
| m | 5 |
| mm | 5000 |
These bound the poster, not the sheet. The paper has its own, smaller limits — see Supported Paper Sizes.
A poster that needs more than 20 sheets on an axis is still reachable: size mode derives the count from the dimensions rather than capping it, so it will build grids grid mode will not. If you are hitting either limit, a larger paper size is usually the better answer than a larger grid.
Related
- Supported Paper Sizes — the sheet sizes the counts above are computed against.
- How to Get Rid of White Gaps When Taping Tiled Prints Together — overlap depends on the margin, which depends on this arithmetic.