Folio Calculator
Sheet layout for different folio sizes (quarto, octavo, etc.).
About this calculator
Traditional bookbinding builds page sizes by repeatedly folding a large parent sheet of paper, and each fold count has a name — folio (1 fold, 4 pages), quarto (2 folds, 8 pages), octavo (3 folds, 16 pages), duodecimo (12 leaves via a combination fold, 24 pages), and sextodecimo (4 folds, 32 pages). This calculator takes your parent sheet's height and width along with the chosen fold type and divides each dimension by that format's width and height divisors to get the untrimmed leaf size — essentially working out how the sheet's original dimensions get carved up as it's folded down. From there it subtracts a standard 3mm trim on the head and tail (the fold edges get trimmed for a clean opening) and 3mm on the fore-edge alone, since the spine edge stays bound and untrimmed, to arrive at the final trimmed page dimensions in both millimeters and inches.
Given your target total page count, it divides by pages-per-sheet, then rounds that figure up so every signature comes out complete, and reports the resulting waste pages — the extra blank leaves that come from needing complete signatures rather than an exact page count. This is a standard, widely-used imposition model, but it assumes straightforward folding without accounting for creep (the slight page-size shift in thick multi-sheet signatures) or non-standard trim allowances some printers use — for a large print run or unusual paper stock, confirm trim margins with your printer before finalizing sheet dimensions.
Inputs
Results
Trimmed page height (mm)
142.5
Trimmed page width (mm)
207
How to Use This Calculator
- Enter the height and width of the unfolded parent sheet in millimeters (e.g., 594 × 420 mm for A2).
- Select the fold type: folio (4 pages), quarto (8), octavo (16), duodecimo (24), or sextodecimo (32).
- Enter the total number of pages needed in the finished book.
- Read the trimmed page height and width in mm and inches — these are the final leaf dimensions after folding and trimming.
- Note the number of parent sheets needed and any waste pages added to complete the last signature.
- Use the pages per sheet output to verify your imposition layout before printing.
How the result changes with Parent sheet height (mm)
| Parent sheet height (mm) | Trimmed page height (mm) | Trimmed page width (mm) |
|---|---|---|
| 297 | 68.3 | 207 |
| 446 | 105.5 | 207 |
| 891 | 216.8 | 207 |
| 1,485 | 365.3 | 207 |
What each input means
- Parent sheet height (mm)
- Height of the unfolded parent sheet in mm (e.g., 594 for A2).
- Parent sheet width (mm)
- Width of the unfolded parent sheet in mm (e.g., 420 for A2).
- Fold type
- 1 = Folio (4pp), 2 = Quarto (8pp), 3 = Octavo (16pp), 4 = Duodecimo (24pp), 5 = Sextodecimo (32pp).
- Total pages needed
- Total number of pages in the finished book.
What each result means
- Trimmed page height (mm)
- Final page height after trimming.
- Trimmed page width (mm)
- Final page width after trimming.
- Page height (inches)
- Trimmed height in inches.
- Page width (inches)
- Trimmed width in inches.
- Pages per sheet
- How many pages come from each parent sheet.
- Sheets needed
- Number of parent sheets to produce the book.
- Untrimmed leaf height (mm)
- Leaf height before trimming.
- Untrimmed leaf width (mm)
- Leaf width before trimming.
- Waste pages
- Extra blank pages from rounding up to full sheets.
How this is calculated
Worked example, using the default values
- Identify Input Parameters4 parametersParent sheet height (mm) = 594, Parent sheet width (mm) = 420, Fold type = 3, Total pages needed = 128 = 4 input(s) provided
- Calculate Trimmed page heightTrimmed page height = sheetHeightMm / fold.heightDivisor142.5 = 142.5
- Calculate Trimmed page widthTrimmed page width = sheetWidthMm / fold.widthDivisor207 = 207
- Calculate Page heightPage height = trimmedHeight / 25.45.61 = 5.61
- Calculate Page widthPage width = trimmedWidth / 25.48.15 = 8.15
Engine last updated . Checked against 3 independently-derived tests — how we verify calculators. Built by Paul Gunder, a software engineer, not a licensed financial, medical, or legal professional.
Frequently Asked Questions
Why does duodecimo (12mo) split the width into thirds instead of following the same power-of-two pattern as the other formats?
Folio, quarto, octavo, and sextodecimo each come from straightforward binary folds (1, 2, 3, and 4 folds respectively), so their divisors are powers of two. Duodecimo is a composite format — 12 leaves come from combining a quarto-style fold with an extra three-way cut rather than a single clean binary fold sequence — which is why its width divisor is 3 instead of 2 or 4.
Why is the fore-edge trim only 3mm while head and tail together get 6mm?
The calculator trims 3mm off each of the head and tail (2 × 3mm = 6mm total) because both are true fold edges that need a clean, even opening cut. The fore-edge only loses one 3mm trim because only the outer edge is a fold-and-cut boundary — the inner spine edge is the bound edge and isn't trimmed at all, so it doesn't get a second 3mm subtracted the way head and tail do.
What causes the "waste pages" output, and can I reduce it to zero?
Waste pages appear because you can only print in whole-sheet increments — the calculator divides your target page count by pages-per-sheet and always produces a whole number of sheets, so any remainder becomes extra blank pages in the final signature. You can only reach zero waste by choosing a total page count that divides evenly by your format's pages-per-sheet (4, 8, 16, 24, or 32 depending on fold type).
Why do the trimmed dimensions matter more than the untrimmed leaf dimensions?
The untrimmed leaf dimensions are just the sheet arithmetic before any cutting — they don't represent a page you can actually read or turn. The trimmed dimensions subtract the head, tail, and fore-edge trim to give the true finished page size your reader will see, so when matching an existing edition's trim size you should work backward from the trimmed figures, not the untrimmed ones.
Related Calculators
The questions that sit next to this one — chosen by subject, including calculators filed under a different category.
Signature Calculator
Number of signatures from page count and fold type.
BookbindingPaper Grain Direction Calculator
Determine correct paper grain orientation for bookbinding and calculate how many grain-correct pages you can cut from a parent sheet.
Printing & PublishingPrint Sheet Layout Calculator
Calculate how many pages fit on a press sheet, optimizing imposition layout with bleed and gutter allowances.
BookbindingBook Block Calculator
Spine width from page count, paper weight, and binding method.
More in Crafts, Hobbies & Games.