Reference
Paper sizes in points
A point is exactly 1/72 inch — the unit inside every PDF page box, every InDesign document and every CSS print stylesheet. This is the full conversion for all 48 standard sizes, in points and picas, with the exact fractional values alongside the rounded ones your software shows.
A4
595 × 842 pt
595.276 × 841.890
A5
420 × 595 pt
419.528 × 595.276
A3
842 × 1191 pt
841.890 × 1190.551
US Letter
612 × 792 pt
exact — inch-defined
Why your PDF says 595.28
ISO sizes are defined in whole millimetres and points are defined against the inch, so converting between them lands on a fraction every time. A4 at 210 mm wide is 210 ÷ 25.4 × 72 = 595.2756 pt. PDF stores that fraction; the interface rounds it for display. Nothing is wrong when your page box reads 595.28 rather than 595 — that is A4.
The US sizes behave differently for the same structural reason the Letter page explains for pixels: they are inch-defined, and 8.5 × 72 is exactly 612. Letter, Legal and Tabloid all give whole points, which is why so much PostScript-era software used them as defaults.
ISO 216 A-series
The worldwide document standard. A0 is derived from one square metre; every size is the previous one halved, rounded to whole millimetres, at a constant 1:√2 ratio.
| Size | Points (rounded) | Points (exact) | Picas | Millimetres |
|---|---|---|---|---|
| A0 | 2384 × 3370 | 2383.94 × 3370.39 | 198.7 × 280.9 | 841 × 1189 |
| A1 | 1684 × 2384 | 1683.78 × 2383.94 | 140.3 × 198.7 | 594 × 841 |
| A2 | 1191 × 1684 | 1190.55 × 1683.78 | 99.2 × 140.3 | 420 × 594 |
| A3 | 842 × 1191 | 841.89 × 1190.55 | 70.2 × 99.2 | 297 × 420 |
| A4 | 595 × 842 | 595.28 × 841.89 | 49.6 × 70.2 | 210 × 297 |
| A5 | 420 × 595 | 419.53 × 595.28 | 35 × 49.6 | 148 × 210 |
| A6 | 298 × 420 | 297.64 × 419.53 | 24.8 × 35 | 105 × 148 |
| A7 | 210 × 298 | 209.76 × 297.64 | 17.5 × 24.8 | 74 × 105 |
| A8 | 147 × 210 | 147.4 × 209.76 | 12.3 × 17.5 | 52 × 74 |
| A9 | 105 × 147 | 104.88 × 147.4 | 8.7 × 12.3 | 37 × 52 |
| A10 | 74 × 105 | 73.7 × 104.88 | 6.1 × 8.7 | 26 × 37 |
ISO 216 B-series
The in-between sizes: each Bn is the geometric mean of An and A(n−1). Used for posters, books and passports where A-steps are too coarse.
| Size | Points (rounded) | Points (exact) | Picas | Millimetres |
|---|---|---|---|---|
| B0 | 2835 × 4008 | 2834.65 × 4008.19 | 236.2 × 334 | 1000 × 1414 |
| B1 | 2004 × 2835 | 2004.09 × 2834.65 | 167 × 236.2 | 707 × 1000 |
| B2 | 1417 × 2004 | 1417.32 × 2004.09 | 118.1 × 167 | 500 × 707 |
| B3 | 1001 × 1417 | 1000.63 × 1417.32 | 83.4 × 118.1 | 353 × 500 |
| B4 | 709 × 1001 | 708.66 × 1000.63 | 59.1 × 83.4 | 250 × 353 |
| B5 | 499 × 709 | 498.9 × 708.66 | 41.6 × 59.1 | 176 × 250 |
| B6 | 354 × 499 | 354.33 × 498.9 | 29.5 × 41.6 | 125 × 176 |
| B7 | 249 × 354 | 249.45 × 354.33 | 20.8 × 29.5 | 88 × 125 |
| B8 | 176 × 249 | 175.75 × 249.45 | 14.6 × 20.8 | 62 × 88 |
| B9 | 125 × 176 | 124.72 × 175.75 | 10.4 × 14.6 | 44 × 62 |
| B10 | 88 × 125 | 87.87 × 124.72 | 7.3 × 10.4 | 31 × 44 |
C-series envelopes (ISO 269)
Envelopes sized to take the matching A-sheet flat — each Cn is the geometric mean of An and Bn. The standard was withdrawn by ISO; its sizes remain what envelope makers sell.
| Size | Points (rounded) | Points (exact) | Picas | Millimetres |
|---|---|---|---|---|
| C0 | 2599 × 3677 | 2599.37 × 3676.54 | 216.6 × 306.4 | 917 × 1297 |
| C1 | 1837 × 2599 | 1836.85 × 2599.37 | 153.1 × 216.6 | 648 × 917 |
| C2 | 1298 × 1837 | 1298.27 × 1836.85 | 108.2 × 153.1 | 458 × 648 |
| C3 | 918 × 1298 | 918.43 × 1298.27 | 76.5 × 108.2 | 324 × 458 |
| C4 | 649 × 918 | 649.13 × 918.43 | 54.1 × 76.5 | 229 × 324 |
| C5 | 459 × 649 | 459.21 × 649.13 | 38.3 × 54.1 | 162 × 229 |
| C6 | 323 × 459 | 323.15 × 459.21 | 26.9 × 38.3 | 114 × 162 |
| C7 | 230 × 323 | 229.61 × 323.15 | 19.1 × 26.9 | 81 × 114 |
| DL | 312 × 624 | 311.81 × 623.62 | 26 × 52 | 110 × 220 |
US traditional sizes
Inch-defined sizes that predate ISO 216 and remain the North American standard. Inch definitions mean exact whole-pixel values at every common DPI.
| Size | Points (rounded) | Points (exact) | Picas | Millimetres |
|---|---|---|---|---|
| US Letter | 612 × 792 | 612 × 792 | 51 × 66 | 215.9 × 279.4 |
| US Legal | 612 × 1008 | 612 × 1008 | 51 × 84 | 215.9 × 355.6 |
| Tabloid / Ledger | 792 × 1224 | 792 × 1224 | 66 × 102 | 279.4 × 431.8 |
| Half Letter | 396 × 612 | 396 × 612 | 33 × 51 | 139.7 × 215.9 |
| Executive | 522 × 756 | 522 × 756 | 43.5 × 63 | 184.1 × 266.7 |
| Government Letter | 576 × 756 | 576 × 756 | 48 × 63 | 203.2 × 266.7 |
| Junior Legal | 360 × 576 | 360 × 576 | 30 × 48 | 127 × 203.2 |
ANSI/ASME Y14.1
The formal US engineering ladder starting from Letter. Areas double each step, but the aspect ratio alternates between 1:1.294 and 1:1.545.
| Size | Points (rounded) | Points (exact) | Picas | Millimetres |
|---|---|---|---|---|
| ANSI A | 612 × 792 | 612 × 792 | 51 × 66 | 215.9 × 279.4 |
| ANSI B | 792 × 1224 | 792 × 1224 | 66 × 102 | 279.4 × 431.8 |
| ANSI C | 1224 × 1584 | 1224 × 1584 | 102 × 132 | 431.8 × 558.8 |
| ANSI D | 1584 × 2448 | 1584 × 2448 | 132 × 204 | 558.8 × 863.6 |
| ANSI E | 2448 × 3168 | 2448 × 3168 | 204 × 264 | 863.6 × 1117.6 |
Architectural (ARCH)
The parallel US series for architectural drawings, in cleaner 3:4 / 2:3 ratios. ARCH B (12×18) is famously confused with ANSI B (11×17).
| Size | Points (rounded) | Points (exact) | Picas | Millimetres |
|---|---|---|---|---|
| ARCH A | 648 × 864 | 648 × 864 | 54 × 72 | 228.6 × 304.8 |
| ARCH B | 864 × 1296 | 864 × 1296 | 72 × 108 | 304.8 × 457.2 |
| ARCH C | 1296 × 1728 | 1296 × 1728 | 108 × 144 | 457.2 × 609.6 |
| ARCH D | 1728 × 2592 | 1728 × 2592 | 144 × 216 | 609.6 × 914.4 |
| ARCH E | 2592 × 3456 | 2592 × 3456 | 216 × 288 | 914.4 × 1219.2 |
Points, pixels and the 96 DPI fiction
Points and pixels get confused because CSS pretends they relate. CSS defines one inch as exactly 96 pixels, which makes 1 pt equal 1.333 CSS px — a fixed ratio that holds no matter what your monitor actually measures. That is a deliberate simplification: it keeps layouts predictable, at the cost of the inch no longer being an inch on screen.
On paper the relationship is real but depends on resolution, which is what the DPI calculator exists for. A4 is 595 pt wide whatever you do; it is 2480 px wide at 300 DPI and 4960 px at 600. Points describe the page, pixels describe the raster you put on it.
Frequently asked questions
What is A4 in points?
A4 is 595 × 842 points when rounded the way PDF tools display it, and 595.276 × 841.890 pt exactly. The fraction appears because A4 is defined in whole millimetres (210 × 297 mm) while a point is a fraction of an inch, so the two systems never align on a round number. Open any A4 PDF and the page box reads 595.28 × 841.89.
Why is a point 1/72 of an inch?
Because Adobe fixed it there when PostScript was designed in the early 1980s, choosing a convenient round divisor over the messier traditional printers’ point. That decision propagated into PDF, which measures every page box and coordinate in points, and from there into InDesign, Illustrator and CSS. Older typographic points differ: the Didot point is about 0.376 mm and the TeX point is 1/72.27 inch — relevant to type history, not to your files.
What is a pica?
Twelve points, so one sixth of an inch, or 4.233 mm. Picas measure column widths and gutters in page layout, where the numbers stay small and whole: an A4 page is 49.6 picas wide. InDesign accepts pica notation as 12p6 meaning 12 picas and 6 points.
Is a CSS pt the same as a PostScript point?
Same definition, different consequence. Both are 1/72 inch, but CSS resolves an inch to exactly 96 CSS pixels no matter what your screen really does, so 1 pt renders as 1.333 CSS px. That makes pt dependable in print stylesheets and misleading for screen layout. Use px or rem for screens and keep pt for paper and PDF.
Which paper sizes come out as whole points?
The inch-defined ones. US Letter is exactly 612 × 792 pt, Legal is 612 × 1008 pt and Tabloid is 792 × 1224 pt, because their inch dimensions multiply cleanly by 72. Every ISO size lands on a fraction instead, since millimetres and inches share no common whole-number base — the same reason ISO sizes never give whole pixel counts either.
Do I need to worry about the rounding?
Rarely. A tenth of a point is about 0.035 mm, far below what any printer resolves or any cutter respects. It matters in two places: when a validation tool compares your page box against a spec to four decimal places, and when many rounded values accumulate in a generated layout. Set the page size from your software’s built-in A4 preset rather than typing 595 × 842 and the exact values are used for you.