Paper size chart & converter

A4 paper size in mm, cm, inches and pixels

A4 is 210 × 297 mm (21 × 29.7 cm), or about 8.27 × 11.69 inches, and it's the standard office paper in most of the world. Here it is in every unit the converter uses, next to US Letter:

A4 vs Letter: what's the difference?

A4 is 5.9 mm (0.23 in) narrower and 17.6 mm (0.69 in) taller than Letter, with about 3.4% more area. The shapes differ too, 1 : 1.414 for A4 against 1 : 1.294 for Letter, so a page laid out for one never fits the other exactly: at 100% scale the edges can be clipped, and a scaled page ends up with uneven margins.

Letter is the standard in the United States and Canada, and the Unicode CLDR locale data that many apps use for default settings also lists it for Mexico, the Philippines and several countries in Central and South America, such as Chile, Colombia and Venezuela. Nearly everywhere else, A4 is the norm.

How to print a Letter document on A4 paper (and vice versa)

1. In the print dialog, set Paper size to the paper that's actually loaded.
2. Turn on scaling. It may be called Fit to page, Scale to fit, Fit to printable area or Shrink oversized pages. A Letter page is scaled to 97.27% to fit A4, and an A4 page to 94.07% to fit Letter, before printer margins.
3. Make sure the printer's own paper setting matches the tray, on its control panel or in its app. If the printer expects Letter but finds A4, many models pause with a paper size mismatch message.
4. If you can edit the file, change its page size instead (Layout → Size in Word, File → Page setup in Google Docs) so the text reflows rather than shrinks.

To confirm nothing is cut off, print our free printer test page, which fits both Letter and A4. If a job gets stuck waiting for the wrong paper, cancel it and send it again; see how to clear stuck print jobs.

ISO A paper sizes (A0 to A10)

The A series comes from ISO 216. A0 has an area of about one square meter, and each smaller size is half of the one above it: cut A3 in half across its long side and you get two A4 sheets. That works because every A size has a 1 : √2 (about 1 : 1.414) shape, so halving never changes the proportions. It's also why copiers scale A4 to A3 at 141% and A3 to A4 at 71% with no cropping or empty margins. Sizes are rounded down to whole millimeters, which is why A5 is 148 mm wide rather than 148.5 mm.

ISO B and JIS B paper sizes

B sizes fill the gaps between A sizes: B4 is larger than A4 but smaller than A3. Japan's JIS B series is slightly larger: JIS B5 is 182 × 257 mm against 176 × 250 mm for ISO B5, and JIS B4 is 257 × 364 mm against 250 × 353 mm. Printer drivers often list “B5 (JIS)” separately, and a plain “B5” in a print menu may mean either, so check the millimeters.

North American paper sizes: Letter, Legal, Tabloid

US sizes are defined in inches. Letter and Tabloid double as ANSI A and ANSI B in the ANSI/ASME Y14.1 drawing sizes: Tabloid is exactly two Letter sheets side by side, and Ledger is the same 11 × 17 in sheet turned landscape. Unlike ISO sizes, they don't share one shape, so enlarging a Letter page to Tabloid leaves empty margins.

Executive is the one to double-check: Windows, PostScript and IPP printer standards define it as 7.25 × 10.5 in, but Adobe's printer description spec notes that the size varies between devices.

Envelope sizes: C4, C5, C6, DL and #10

The ISO C envelope sizes sit between the A and B series, so an A4 sheet fits a C4 envelope flat, a C5 folded once and a C6 folded twice. DL, a common business envelope, takes A4 folded in thirds, and the US #10 does the same for Letter. When you print envelopes, select the envelope size in the print dialog and load it the way your printer's manual shows, since the flap side and direction vary by model.

Photo print sizes in inches and cm

A 4 × 6 in photo is 10.16 × 15.24 cm. The metric 10 × 15 cm size is slightly smaller (1.6 mm narrower and 2.4 mm shorter), so pick the size printed on your photo paper pack. Shape matters as much as size: 4 × 6 has the 2:3 shape of most DSLR photos, but many phones shoot 4:3, so part of the picture is cropped (or you get white borders) on 4 × 6 paper, and a 3:2 photo loses about a sixth of its length on 8 × 10 (4:5). To check whether a photo has enough pixels for a sharp print, use the print size calculator.

A4 and Letter size in pixels at every DPI

Pixel size depends on resolution: pixels = inches × DPI, rounded to the nearest whole pixel. As a rule of thumb, 300 DPI gives sharp prints and 150 DPI is fine for drafts or posters seen from a distance. 96 DPI is the reference pixel web browsers use (CSS defines 1 inch as 96 px), and at 72 DPI the numbers match the page size in points, the unit PDF files use. Strictly, image resolution is PPI (pixels per inch) while printer DPI counts ink dots, but DPI is the everyday term.

How to read the converter results

Results marked Exact involve no rounding; the rest are rounded, using 1 in = 25.4 mm exactly and 1 pt = 1/72 in. The Fit figure is the scale that fits the whole sheet onto the comparison paper in the same orientation. Most printers can't print right to the edge unless borderless printing is on, so the real fit is slightly smaller.