How wide should your margins be?

A margin does three jobs at once, and designs that only think of the first produce the books that feel wrong in the hand: pages so wide the eye drowns, or so tight the words disappear into the spine.

The jobs: the margins keep the text away from where fingers hold the page and where the trim and the binding take their cut; they carry the furniture — running head, page number, notes; and they set the measure, the width of the line of text itself. The first two are guardrails. The third is design, and it is where the decision actually lives.

The measure is the real variable

Typographers have agreed on this for a century: comfortable prose runs 45 to 75 characters per line, with 60 to 70 the centre. Under 45, the eye turns too often and the rhythm stutters. Over 75, it loses its place returning to the left margin — the most common complaint about a badly set wide page, and the reason the reader cannot say why the page feels like work.

The count is in characters, not inches, because the same width carries different amounts of text at different type sizes. Four inches at 11 point is a good measure; four inches at 8 point is a newspaper.

Working numbers: a serif text face at 11 point runs roughly 13 to 15 characters per inch. That conversion is all you need, because margins and type size together must land in the band:

Page	Margins	Text block	At 11 pt
5.5 × 8.5″	0.8″ inside, 0.8″ outside	3.9″	~50–58 characters — good
6 × 9″	0.9″ inside, 0.85″ outside	4.25″	~55–63 — good
6 × 9″	0.5″ both sides	5.0″	~65–75 — the legal edge
8.5 × 11″	1″ both sides	6.5″	~85–95 — too wide for prose

That last row is why large-format pages get wider margins, two columns, or both. An 8.5 × 11 workbook set as a single wide column is not a style choice; it is a measure that reads badly, whatever the content.

The four margins are not equal

The inside margin is set by the binding, not by taste. A bound book never opens flat: the pages curve into the spine, and text near the gutter falls into the curve. The thicker the book, the sharper the curve — which is why the inside margin grows with the page count in the platform requirements, from 0.375 inches for a slim book to 0.875 past 700 pages. The bands are in formatting for KDP. Those are minimums a book can legally sit on and still feel cramped; most trade books carry more.

The bottom margin is usually the deepest. The page number sits there, and the optical centre of a page sits slightly high — a text block placed dead centre looks as if it is sliding off the bottom. A common starting shape is head 0.75″, outside 0.75–0.9″, foot 0.9–1.1″, gutter per the page count.

The head margin carries the running head if the book has one, and the design has to budget for both: a running head at 0.5 inches from the trim edge and the text starting 0.85 inches down leaves the furniture breathing without pushing the block off the page.

What the platform says, and what it cannot

Print-on-demand minimums — 0.25 inches for outside, top and bottom without bleed, plus the gutter bands — are floors, not settings. A book that meets them exactly is legal and usually ugly: a 6 × 9 page with a 0.25-inch outside margin has a measure no prose wants.

The minimums also cannot know what your page is doing. A children’s book with a large type size needs a wider measure or a wider margin than the same trim at 11 point; a poetry collection wants both a narrow measure and generous margins, which is a stylistic decision the requirements have no opinion on. Minimums say what a printer will accept. The measure says what a reader will enjoy, and only the second is design.

Wide margins as a statement

Margins are also legible to readers as register, even when they cannot name it. Poetry, gift books and literary editions run wide margins and small text blocks because the whiteness is part of the object. Dense commercial paperbacks run tight because portability and cost lead. Neither is wrong; both are consistent choices, and a book that splits the difference — generous margins around a cramped measure, say — gets the cost of the generosity and none of the look.

---

Margins set the measure, the measure sets the words per page, and the words per page set the page count — which is why margin decisions ripple into spine width, printing cost and the KDP gutter bands, and why the count is an output rather than an input, as estimating your page count works through.

Nueel’s designs start from measures that already sit in the 45–75 band for their trim, and every margin is a control you can move — with the page count, the gutter requirement and the platform checks updating as the text reflows.

Common questions

What are standard book margins?

Outside margins of roughly 0.75 to 1 inch, a top margin around 0.75 to 1 inch including the running head, and a bottom margin slightly deeper, because the page number lives there. The inside margin is set by the binding: it starts near the others and grows with the page count, from about 0.375 inches for a slim book to 0.875 or more past 700 pages.

How long should a line of text be?

Between 45 and 75 characters, with 60 to 70 the comfortable centre for prose. Below about 45 the eye turns too often; above about 75 it loses the start of the next line. The count is characters, not inches, because the type size decides how much a given width carries.

Why does the inside margin need to be bigger?

The binding. A bound book never opens flat: the pages curve into the spine and the text nearest the gutter falls into shadow and curvature. The thicker the book, the sharper the curve, which is why the requirement grows in bands with the page count rather than being one number.

Do wider margins mean fewer words per page?

Yes, roughly proportionally. Opening all four margins by a quarter inch takes about 10 per cent of the text block's area, and the page count rises to match. Wide margins are a real design choice, not a free one — poetry and gift books pay for them in pages, knowingly.