How to use the Paper Size Chart
- Find a size. Type in Search sizes: a name (“A4”, “tabloid”), a use (“envelope”, “postcard”) or a pair of numbers (“9x12”, “210x297”). The chips narrow the table to one family — A, B, C, US, ANSI, Arch or drawing pads.
- Set your resolution. Enter a value in Pixels at … DPI or tap one of the common values. The pixel column updates for every row, so you can set up a digital canvas that prints at exactly that size.
- Flip the orientation with Portrait or Landscape; all three units swap width and height.
- Compare sizes to scale. Tick the box beside up to eight sizes in the table. The drawing overlays them from a shared bottom-left corner with a scale bar, and the Comparing list shows their exact dimensions; press × there to drop one.
- Take the numbers with you. Copy on any row copies that size in millimeters, inches and pixels. Copy table pastes cleanly into a spreadsheet, and Download CSV saves the rows you have filtered.
How the A, B and C series fit together
The international sizes in ISO 216 rest on one idea: a sheet whose sides are in the ratio 1 : √2 (about 1 : 1.414) keeps the same shape when you cut it in half. A0 is defined as one square meter, which rounds to 841 × 1189 mm. Halve it across the long side and you get A1, halve again for A2, and so on down to A10, rounding each result down to a whole millimeter. A4 is 210 × 297 mm, and 297 ÷ 210 = 1.414.
That ratio is why you can scale an A4 drawing to A3 on a photocopier at 141% without cropping or white margins, and shrink A3 to A4 at 71%. US sizes don’t share a constant ratio: Letter is 1 : 1.294, Tabloid 1 : 1.545, so enlarging Letter artwork onto Tabloid always leaves extra space or crops.
The B series fills the gaps. Each B size is the geometric mean of two neighboring A sizes, so B1 (707 × 1000 mm) sits between A0 and A1; posters and books often use B sizes. The C series, defined in ISO 269, is for envelopes and sits between A and B: a C4 envelope holds an A4 sheet flat, C5 takes A4 folded once, and C6 takes it folded twice.
One trap: Japan’s JIS B sizes are not the ISO B sizes. JIS B5 is 182 × 257 mm, while ISO B5 is 176 × 250 mm. If a Japanese sketchbook says B5, it means the larger one.
Near-misses that cause real problems
| Pair | Dimensions | Difference |
|---|---|---|
| A4 vs Letter | 210 × 297 mm vs 215.9 × 279.4 mm | A4 is 5.9 mm narrower and 17.6 mm taller |
| A3 vs Tabloid | 297 × 420 mm vs 279.4 × 431.8 mm | A3 is 17.6 mm wider and 11.8 mm shorter |
| ANSI A vs Arch A | 8.5 × 11 in vs 9 × 12 in | Arch A is half an inch wider and an inch taller |
| Letter vs Legal | 8.5 × 11 in vs 8.5 × 14 in | Same width, Legal is 3 in taller |
These differences are small enough to ignore on screen and big enough to ruin a print. Artwork laid out for A4 and printed on Letter loses the bottom or gets scaled to 94%; a zine laid out on Letter loses its outer edges on A4 paper. Open the comparison with A4 and Letter ticked to see exactly where each sheet sticks out.
The architectural Arch sizes alternate between 3 : 4 and 2 : 3 proportions (9 × 12, 12 × 18, 18 × 24, 24 × 36, 36 × 48 in), which is why 18 × 24 and 24 × 36 are also standard poster and frame sizes in the US. ANSI sizes double from Letter: ANSI B is two ANSI A sheets, ANSI C is two ANSI B.
Pixels for print
A pixel size only means something together with a DPI value. At 300 DPI, the usual target for prints viewed at arm’s length, A4 needs 2480 × 3508 pixels and Letter needs 2550 × 3300. A 9 × 12 in sketchbook page scanned at 300 DPI comes out at 2700 × 3600. Large posters seen from across a room often look fine at 150 DPI, which halves both numbers. To work backward from an image you already have, use the DPI & Print Size Calculator.
Tips from practice
Print templates at “Actual size”. Most print dialogs default to “Fit” or “Shrink to page”, which quietly scales everything by a few percent. For guide sheets, grids and anything measured, choose 100% or Actual size.
Ask the print shop about bleed before you export. Artwork that runs to the edge needs extra image beyond the trim, commonly 3 mm or 1/8 in per side. An A4 print with 3 mm bleed is a 216 × 303 mm file.
Leave room for the printer’s margin. Home printers can’t print to the edge of the sheet. Keep important lines at least 5 mm (about 1/4 in) inside, or use the borderless mode if your printer has one.
Check frame sizes before you pick paper. US frames and mats are cut for inch sizes, while A-size art from Europe needs custom mats. For stretched canvases, see the Standard Canvas Sizes Chart.