Page Sizes

The common paper sizes, their dimensions, and how big they actually are next to each other. All sizes are given portrait; turn them on their side for landscape. The overlays are proportional, not life-size.

The A series

ISO 216. A0 is exactly one square metre, and every step halves the one before it by folding the long side in two. That only works because the sides are in a 1 : √2 ratio — the one ratio that keeps its shape when halved, so every A size is the same rectangle.

A0 841 × 1189 mm / 33.11 × 46.81 in A1 594 × 841 mm / 23.39 × 33.11 in A2 420 × 594 mm / 16.54 × 23.39 in A3 297 × 420 mm / 11.69 × 16.54 in A4 210 × 297 mm / 8.27 × 11.69 in A5 148 × 210 mm / 5.83 × 8.27 in A6 105 × 148 mm / 4.13 × 5.83 in

ISO A series
Size	mm	in	Ratio	Typical use
A0	841 × 1189	33.11 × 46.81	1 : 1.414	Full-size posters, plots. Exactly 1 m².
A1	594 × 841	23.39 × 33.11	1 : 1.416	Posters, flip charts.
A2	420 × 594	16.54 × 23.39	1 : 1.414	Large drawings, mid-size posters.
A3	297 × 420	11.69 × 16.54	1 : 1.414	Two A4s side by side.
A4	210 × 297	8.27 × 11.69	1 : 1.414	The office page everywhere but North America.
A5	148 × 210	5.83 × 8.27	1 : 1.419	Notebooks, paperbacks, flyers.
A6	105 × 148	4.13 × 5.83	1 : 1.41	Postcards, pocket notebooks.
A7	74 × 105	2.91 × 4.13	1 : 1.419	Index cards, tickets.
A8	52 × 74	2.05 × 2.91	1 : 1.423	Card-sized.

A4 against Letter

They are close enough to be annoying and different enough to reflow a document. A4 is narrower and taller; Letter is wider and shorter. Legal is Letter's width stretched three inches longer, which is why it has its own proportions entirely.

Tabloid / Ledger

Legal

Letter

A3 297 × 420 mm / 11.69 × 16.54 in Tabloid / Ledger 279.4 × 431.8 mm / 11 × 17 in Legal 215.9 × 355.6 mm / 8.5 × 14 in A4 210 × 297 mm / 8.27 × 11.69 in Letter 215.9 × 279.4 mm / 8.5 × 11 in

North American
Size	mm	in	Ratio	Notes
Tabloid / Ledger	279.4 × 431.8	11 × 17	1 : 1.545	Tabloid portrait, Ledger landscape.
Legal	215.9 × 355.6	8.5 × 14	1 : 1.647	Long and narrow; US legal filings.
Letter	215.9 × 279.4	8.5 × 11	1 : 1.294	The office page in the US and Canada.
Executive	184.1 × 266.7	7.25 × 10.5	1 : 1.448	Letterhead and stationery.
Half Letter	139.7 × 215.9	5.5 × 8.5	1 : 1.545	Letter folded in half; digest books.
Junior Legal	127 × 203.2	5 × 8	1 : 1.6	The legal pad.
No. 10 envelope	104.8 × 241.3	4.13 × 9.5	1 : 2.303	Holds Letter folded in three.

B and C

B sizes sit between two A sizes (B4 is between A4 and A3), which is what you want for a poster or a book that should not look like office paper. C sizes are the envelopes: Cn holds an unfolded An, and each fold moves you one size down.

ISO B series
Size	mm	in
B1	707 × 1000	27.83 × 39.37
B4	250 × 353	9.84 × 13.9
B5	176 × 250	6.93 × 9.84
B6	125 × 176	4.92 × 6.93
B7	88 × 125	3.46 × 4.92

ISO C series (envelopes)
Size	mm	in
C4	229 × 324	9.02 × 12.76
C5	162 × 229	6.38 × 9.02
C6/C5	114 × 229	4.49 × 9.02
C6	114 × 162	4.49 × 6.38
DL	110 × 220	4.33 × 8.66

Cards

The small end, where a credit card is the most reliable ruler you own. Index cards come in inches in North America and in A sizes in Europe, and the pairs are close but never equal.

Index 5 × 8

Index 4 × 6

Index 3 × 5

ID-1 credit card

A5 148 × 210 mm / 5.83 × 8.27 in Index 5 × 8 127 × 203.2 mm / 5 × 8 in A6 105 × 148 mm / 4.13 × 5.83 in Index 4 × 6 101.6 × 152.4 mm / 4 × 6 in Index 3 × 5 76.2 × 127 mm / 3 × 5 in A7 74 × 105 mm / 2.91 × 4.13 in ID-1 credit card 85.6 × 54 mm / 3.37 × 2.13 in

Cards and photos
Size	mm	in	Notes
Index 5 × 8	127 × 203.2	5 × 8
Index 4 × 6	101.6 × 152.4	4 × 6	Recipe and Zettelkasten card.
Index 3 × 5	76.2 × 127	3 × 5	The classic index card.
Photo 4 × 6	101.6 × 152.4	4 × 6	Same sheet as the 4 × 6 card.
Business card (JP)	91 × 55	3.58 × 2.17	Meishi — the largest of the three.
Business card (EU)	85 × 55	3.35 × 2.17
Business card (US)	88.9 × 50.8	3.5 × 2
ID-1 credit card	85.6 × 54	3.37 × 2.13	ISO/IEC 7810; the handiest real-world ruler.

Worth knowing

Scaling between the two systems. A4 → Letter is 94%, Letter → A4 is 97%, A3 → Letter is 66%. Two pages per sheet is 71% on A4 (√2 ÷ 2, the number on the photocopier button) but 64% on Letter, which is why 2-up on Letter leaves a strip of white down the side.
Half a Letter sheet is 139.7 × 215.9 mm. A B6+ notebook page (125 × 190) fits it at true size with 7 mm to spare; A5 does not — at 148 mm it is 8 mm too wide, so the best you get is 94%.
Paper weight. gsm is the weight of one square metre, so an A4 sheet weighs gsm ÷ 16 grams: 80 gsm A4 = 5 g exactly. US “20 lb bond” ≈ 75 gsm.
JIS B is not ISO B. Japan's B4 is 257 × 364 mm against ISO's 250 × 353 mm — different paper with the same name.
Engineering sizes. ANSI A–E double Letter each step (ANSI B = Tabloid, 11 × 17 in; ANSI E = 34 × 44 in). ARCH A–E are the architectural set at 4:3 and 3:2 (ARCH D = 24 × 36 in).
Printing. Full-bleed artwork wants ~3 mm (⅛ in) of bleed past the trim and a safe margin the same distance inside it.