Book Interior Layout Preview
Page geometry
Page preview
A book page is a rectangle divided deliberately. The text block is smaller than the page so the margins can do their work: the inner margin protects the text from the gutter, the outer margin holds the reader's thumbs, and the top and bottom margins carry the running head and the folio. Every one of those decisions is measured in millimetres in production.
Production measurements
| Measure | Value |
|---|---|
| Page | 148 × 210mm |
| Text block | 114 × 166mm (61% of the page) |
| Inner / outer margins | 18 / 16mm — inner ≥ outer by 2mm |
| Head / foot margins | 20 / 24mm — foot ≥ head for the folio |
| Lines per page | 32 |
| Characters per line | 62 (in the 45–75 band) |
@page {
size: 148mm 210mm;
margin: 20mm 16mm 24mm 18mm;
}
.book-page {
font-family: 'Source Serif 4', serif;
font-size: 10.5pt;
line-height: 14pt;
text-align: justify;
hyphens: auto;
widows: 2;
orphans: 2;
}
.book-page .folio { font-size: 8.92pt; letter-spacing: 0.04em; }You Might Also Need
The book interior layout preview lays out a page with the five regions a book page actually has, then reports the proportions between them. The measurements are the ones a print production sheet asks for: text block size, margin ratios, lines per page and the resulting characters per line.
What is Book Interior Layout Preview?
The book interior layout preview takes a page size, a type size and leading, and four margin values, then draws the resulting page and reports the geometry a production sheet needs, including the margin ratios between the regions.
- Page width runs from 100mm to 230mm and height from 140mm to 330mm, defaulting to 148 by 210mm, which is A5.
- Body size spans 6pt to 14pt in quarter-point steps and leading from 8pt to 22pt, defaulting to 10.5pt on 14pt.
- Inner, outer, head and foot margins are all adjustable, and the folio position is set independently in millimetres from the trim.
- Lines per page is derived from the text block height less 6mm, divided by the leading converted from points to millimetres at 0.3528.
- Characters per line is estimated from the text block width in points divided by the body size multiplied by 0.5, and the verdict names whether it falls in the 45 to 75 band.
The five regions are what make a book page different from a web container. The text block is smaller than the page so the margins can do their work: the inner margin protects the text from the gutter, the outer margin holds the reader's thumbs, and the head and foot margins carry the running head and the folio. The panel states two of the conventions as measurements rather than rules — the inner margin should be at least as large as the outer for a page that is bound, and the foot margin should be at least as deep as the head margin because the folio sits there. The ink-on-page share reports the text block as a percentage of the whole page, which is the quickest way to see whether a page has been over- or under-margined. The generated print CSS writes the @page rule with the four margins in the correct order, justifies the body with automatic hyphenation, sets widow and orphan control to two lines, and sizes the folio at 85 percent of the body.
- One page is modelled, so a facing-page spread and the creep that appears in a thick book at the gutter are not shown.
- The baseline grid is not drawn, so a leading that does not divide the block evenly shows up only in the lines-per-page figure.
- The margin conventions are reported as measurements without being enforced, so a page with the outer margin deeper than the inner still renders.
- Characters per line is an estimate based on an average character width rather than the chosen face.
- The folio is drawn as a placeholder number rather than a real page number, and no running head beyond the text you supply is set.
Use it when a book's page geometry is being decided, since the text block and margin proportions are the decisions that are expensive to revisit once a book is set, and again when a pre-existing trim size has to be checked against a comfortable line count. The lines per page figure is also what a production plan is built from, because it converts into an extent once the word count is known. Where the pages need what each one carries at the top, the running head previewer works that out, the widow and orphan detector finds the bad breaks before they reach proof, and the baseline grid calculator checks that the leading divides the block evenly.
How to use Book Interior Layout Preview
- Set the page width and height, either to a standard trim size or to the dimensions the job specifies.
- Enter the body size and leading, which together decide how many lines the text block will hold.
- Adjust the inner, outer, head and foot margins and the folio position, watching the text block share and the lines per page readouts.
- Check the characters per line verdict, then copy the print CSS, which writes the page rule, the margins and the folio size.
When to use Book Interior Layout Preview vs related tools
Reach for it when a book's trim size and margins are being decided, when a publisher has supplied a page size and you need to know what type size will fit it comfortably, or when an existing layout is producing a line count that does not suit the manuscript. It is the tool that turns a margin scheme into numbers that can be argued with. For the running head and folio placement, the running head previewer is the companion, the widow and orphan detector catches the failures that appear once the text flows, and the print type specification sheet records the resulting sizes in points for the printer.
Privacy & Security
This tool runs entirely in your browser — no data ever leaves your device. There is no server round-trip, no upload, no logging, and no account required. Your input is processed locally using client-side JavaScript and is never stored, transmitted, or accessible to anyone else. When you close the tab, everything disappears.