What changes when the undo button doesn't come with it
A screen is forgiving in a way that shapes how people solve on it without their ever noticing. You can drop a digit into a square to see how the rest of the row reacts, decide you dislike it, and take it back with a keystroke; the board keeps a tally of the placements that turned out to be wrong and tells you the moment one of them is. Take the same puzzle to a printed sheet and every one of those safety rails is gone at once. There is no counter. There is no step backwards. A digit that shouldn't be there simply sits quietly in its square until, twenty minutes later, two 4s meet in a column and the whole afternoon has to be unpicked.
This is not an argument against paper — it is the reason a lot of people prefer it. What it does mean is that solving well on paper is a slightly different skill, and the difference is almost entirely about how you handle the things you are not yet sure of.
Marks you can afford to be wrong about
On screen there is a button that fills every empty square with its candidates in one action, and undoes the lot in one more, so writing marks costs nothing and there is no reason to be sparing. A pencil has no such button at either end. Filling a whole grid by hand takes several minutes of careful transcription, and a single misread square poisons the marks around it in a way that is very hard to spot afterwards, because a wrong mark looks exactly like a right one.
The habit that survives contact with paper is to mark narrowly and late. Work a house at a time rather than the board at a time: when a row or a box is down to three or four empty squares, pencil the possibilities into just those squares, take whatever the position gives you, and move on. You end up writing perhaps a fifth of the marks, each one on a square you are actively thinking about, and an error stays local to the corner of the grid where you made it.
Why a wrong digit costs more than a slow one
There is a second habit worth borrowing from people who solve competitively on paper: write your own entries in a visibly different hand from the printed clues — smaller, or nearer a corner of the square. It looks fussy for about four puzzles. Then the first time a grid goes wrong you will be able to tell at a glance which digits were given to you and which you invented, and you will be able to rub out the second group and keep the first rather than starting the sheet again. Printing two copies of the same puzzle is the cruder version of the same insurance, and the builder above will happily give you two.
How many to a sheet, and what each density costs
The per-page setting is the one that decides whether a pack is pleasant to solve, and it is worth knowing what it does in millimetres rather than guessing. Every grid in these packs is drawn as large as the sheet allows once the header, the caption and the margins have taken their share, so the numbers below are what actually comes out of the printer on A4.
| Per sheet | Grid | Square | Suits |
|---|---|---|---|
| One | 177mm | 19.7mm | Large print: older eyes, or a classroom wall |
| Two | 103mm | 11.5mm | The default — about what a newspaper prints, with room to pencil in |
| Four | 84mm | 9.4mm | Tighter, but still markable |
| Six | 62mm | 6.9mm | Most puzzles to the page, fewest to the square |
Divide a square by three and you have the room one pencil mark gets. At six to a sheet that is about 2.3mm, which is a setting for solving in your head — or for someone with a very sharp pencil and good light.
One genuine oddity worth knowing if you have both paper sizes available. US Letter is wider than A4 but noticeably shorter, so which one gives the bigger grid depends entirely on how the grids are stacked. At two to a sheet the sheets are stacked vertically and height is the binding constraint, so A4 wins by nearly a centimetre — 103mm against 95mm. At four to a sheet the grids sit two abreast, width starts to matter, and Letter takes the lead at 87mm against 84mm. If you are printing large-print singles, Letter is very slightly better again, at 183mm.
Getting it out of the printer intact
The file is drawn as vector artwork rather than as a picture of a grid, which has two consequences that matter. The rules and digits come out at whatever resolution your printer runs at instead of at whatever resolution an image was saved at, so the lines are genuinely crisp rather than nearly crisp. And the file stays small: twelve puzzles laid out two to a sheet with a full answer key is around 75KB, which is a fraction of what a single scanned page would be, and light enough to email to someone without thinking about it.
Every print dialogue has a scaling control, and it usually defaults to something like "Fit to printable area". These sheets are already laid out for the paper size you chose, with their own margin built in, so fitting them again shrinks the whole page by a few percent and pushes the grids inward for no gain. Set scaling to "Actual size" or 100% and turn off the browser's own headers and footers, and what you get on the paper is what you saw in the preview.
Colour is never required. Everything is drawn in black and greys, and the killer packs mark their cages with dashed boundaries rather than the tinted fills the screen board uses, for reasons the killer sudoku page goes into — so a monochrome laser printer loses nothing at all. The one thing to think about before you send a long pack double-sided is the answer key, which lives at the back: with an odd number of puzzle sheets the first page of answers ends up on the reverse of the last page of puzzles, which is not where you want it. Print the answers as a separate job, or leave them out and keep the solutions on the screen instead.
One booklet, five different boards
Each of the game pages on this site carries a pack builder of its own, and each of those is deliberately locked to the board it sits beneath: the panel under the jigsaw grid prints jigsaw puzzles and nothing else, which is the correct behaviour for someone who arrived there to play jigsaw. This page is the exception, and it is the reason it exists rather than being a second copy of the classic one. Set the board to Mixed and a single booklet will rotate through classic, jigsaw, killer, X-sudoku and 6×6 grids in turn. Set the difficulty to Mixed as well and the two rotations advance at different lengths, which is what stops a booklet settling into a pattern.
Five boards against four levels: twenty sheets before any pairing comes round twice.
In a mixed pack the line above each grid names its board as well as its level, because the shape of a puzzle is not always obvious from a glance at the printed rules and you need to know whether those dashed lines are cages before you start. That naming is switched off in a single-board pack, where the title at the top of every sheet has already answered the question and repeating it fifty times would just be noise. The title is yours to write, incidentally: the name you type is printed on every sheet and stored in the file's properties, which is the difference between a stack of loose paper and something you can hand to a person.
Two honest limits on the mixing, both worth knowing before you commit fifty sheets to the printer:
- Only classic has the curated banks behind it that make Evil and Extreme mean something, so those two levels are offered for classic packs alone.
- A 6×6 grid genuinely supports three levels rather than four, so an Expert mixed pack prints its small grids at Hard — and labels them Hard, rather than quietly calling them something they are not.