Choosing a page size and margins

Every other option in the converter is a preference. The page size is a decision, and it changes everything downstream: how many pages you get, how large the type reads, whether it prints correctly, and whether you spend the whole book pinching and panning.

The reason it matters so much is that the two things you might do with the file want opposite answers.

For paper: match the tray

A4 if you are anywhere except the US and Canada. US Letter if you are.

That is the whole rule, and it is not a preference. It is a physical fact about the paper in your printer. A4 is 210 × 297mm; Letter is 216 × 279mm. Print a Letter-sized PDF on A4 and you lose 6mm off the width and gain 18mm of white at the foot. Print an A4 one on Letter and the reverse. Neither is catastrophic, and neither looks right.

A5 is worth knowing about. It is exactly half an A4 sheet, which means you can print two pages to a side and cut, and you get something the size and proportion of an actual paperback. It uses more sheets than A4 but far less paper per word than you would guess, because A4 at a readable type size wastes a lot of line length.

Trade paperback, 6 × 9 inches, is what most print-on-demand services use. Pick it if the PDF is going to one.

For screens: match the screen

Here the instinct almost everybody has is wrong, so it is worth being explicit.

If the text is too small on a tablet, make the page smaller, not the type bigger.

A PDF reader scales the whole page to fit the screen. So:

• 11pt on A4 gives you about 90 characters per line, on a page then squeezed onto a 10-inch display. The type arrives tiny.
• 14pt on A4 gives you about 70 characters per line, on a page squeezed to the same size. Slightly bigger type, a third more pages, still not comfortable.
• 11pt on a phone-shaped page gives you about 35 characters per line. When that narrow page is scaled up to fill the screen, every character is nearly three times the size it was in the first case.

Same type size, completely different reading experience. The page size is the zoom control; the type size barely moves the needle.

So: Tablet screen (4:3) for an iPad or most Android tablets. Phone screen (16:9) for a phone. Both match the shape of the display, so a page fills it with no letterboxing.

Margins

Normal is right for almost everything.

Narrow if you are printing something long and care about the paper, or if you are reading on a screen. Screen margins are wasted space, since nobody holds a tablet by the paper.

Wide if the pages are going into a ring binder, comb or coil. The punched edge takes about 15mm, and Normal margins put your text right up against the holes. Wide is also the one to pick if you intend to write in it.

Type size, briefly

• 10pt — dense. Fine for reference material you scan rather than read.
• 11pt — a book. This is the default and it is the default for a reason.
• 12pt — comfortable, and about 10% more pages.
• 14pt — genuine large print.

One warning: type looks larger on a backlit screen than it does on paper, and almost everyone judging on a monitor picks one size too small. Print two pages before you commit.

A rough sense of length

At 11pt with normal margins, an average novel of 100,000 words comes out at roughly:

• A4 — 170 pages
• A5 — 300 pages
• Trade paperback — 320 pages
• Tablet — 240 pages
• Phone — 600 pages

The converter shows you its own estimate as soon as you change the setting, which is more accurate than this table because it has actually counted your book.