What size is A6 paper?

105 by 148 mm, which is 4.13 by 5.83 inches. The millimetres are the defining dimensions here: A6 comes out of ISO 216, which fixes A0 at 841 by 1189 mm and makes every size below it the one above halved across its long side and rounded down to the whole millimetre. The inches are the conversion.

Is A6 the same as a postcard or a 4 by 6 photo?

A6 is the standard postcard size in most of the world, so postcard and A6 usually mean the same thing. A 4 by 6 photo print is not the same: A6 is 3.4 mm wider and 4.4 mm shorter, so neither one fits inside the other. Printing an A6 design on 4 by 6 paper crops the sides or leaves a strip at one end.

How does A6 relate to A4 and A5?

Two A6 sheets side by side make A5, and folding A6 in half gives A7. A6 is a quarter of A4: fold A4 in half for A5 and in half again for A6, so four A6 cards come out of one A4 sheet, to within the millimetre ISO 216 rounds away at each halving.

How many pixels is A6 at 300 dpi?

1240 by 1748 in portrait, and 620 by 874 at 150 dpi or 298 by 420 at 72 dpi. Because A6 is defined in millimetres, the inch dimensions are not round numbers and the pixel counts are rounded to the nearest whole pixel, so an A6 canvas at 300 dpi is 1240 pixels wide rather than exactly 1240.157.

Is A6 exactly 1 to root 2 like the other A sizes?

Almost. ISO 216 rounds each halving down to whole millimetres, which leaves A6 at 1 to 1.4095 rather than the ideal 1 to 1.4142. That is a real difference of about a third of a millimetre across the width, and it is why pages that print 1:1.414 against every size are stating something false about the small ones.

A6 Paper Size

A6 is 105 by 148 mm, or 4.13 by 5.83 inches. The tool above opens on A6 drawn to scale against a 4 by 6 photo print, because those two are close enough to be mistaken for each other and are not the same sheet. The table below gives A6 in millimetres, centimetres, inches and pixels at 72, 150 and 300 dpi, in both portrait and landscape.

A6 · 105 × 148 mm
4 × 6 photo · 101.6 × 152.4 mm

A6 · ISO A series105 × 148 mm4.13 × 5.83 in · 1240 × 1748 px at 300 dpi

Size

Compare with

Units

A6 is 3.4 mm wider and 4.4 mm shorter than 4 × 6 photo.

Millimetresthe defining dimensions
105 × 148 mm
Centimetres
10.5 × 14.8 cm
Inchesconverted from millimetres
4.13 × 5.83 in
Pixels at 72 dpiscreen
298 × 420 px
Pixels at 150 dpidraft print
620 × 874 px
Pixels at 300 dpiphoto and press print
1240 × 1748 px
Aspect rationominally 1 to root 2
1 : 1.41
Area0.01554 m²
155.4 cm² · 24.09 in²
Against 4 × 6 photowhich goes inside which
Neither fits inside the other: A6 is the wider sheet and 4 × 6 photo is the taller one.

Postcards, index cards and small flyers.
The sides are in the ratio 1 to the square root of 2, so folding a sheet from this series in half across its long side leaves the same shape.
Two A6 sheets side by side make A5, and folding A6 in half gives A7.
ISO 216 rounds each halving down to whole millimetres, which leaves this size a little off that exact ratio: it is 1 : 1.4095, not 1 : 1.4142.
4 × 6 photo is 3.4 mm narrower and 4.4 mm taller.

The A series, A0 to A10

Every size below A0 is the one above it halved across the long side, rounded down to the whole millimetre. That is the rule ISO 216 states, and it is the rule these numbers come from.

Millimetres	Inches	Pixels at 300 dpi	Used for
841 × 1189	33.11 × 46.81	9933 × 14043	The base sheet the whole A series is halved from.
594 × 841	23.39 × 33.11	7016 × 9933	Large posters and flip charts.
420 × 594	16.54 × 23.39	4961 × 7016	Medium posters and technical drawings.
297 × 420	11.69 × 16.54	3508 × 4961	Charts, spreads and oversized printouts.
210 × 297	8.27 × 11.69	2480 × 3508	The standard document sheet almost everywhere.
148 × 210	5.83 × 8.27	1748 × 2480	Notebooks, flyers and folded A4 leaflets.
105 × 148	4.13 × 5.83	1240 × 1748	Postcards, index cards and small flyers.
74 × 105	2.91 × 4.13	874 × 1240	Pocket notes and small tickets.
52 × 74	2.05 × 2.91	614 × 874	Small labels and card-sized cuts.
37 × 52	1.46 × 2.05	437 × 614	Tiny labels and tags.
26 × 37	1.02 × 1.46	307 × 437	The smallest A cut, used for stamps and labels.

North American sizes

Defined in inches, so the millimetres are the conversion and the pixel counts are exact whole numbers at every DPI.

Millimetres	Inches	Pixels at 300 dpi	Used for
215.9 × 279.4	8.5 × 11	2550 × 3300	The default sheet in the US, Canada and Mexico.
215.9 × 355.6	8.5 × 14	2550 × 4200	US contracts and legal pads, three inches longer.
279.4 × 431.8	11 × 17	3300 × 5100	US newspapers, spreads and two-up Letter.
184.15 × 266.7	7.25 × 10.5	2175 × 3150	US letterheads and memos, just under Letter.
139.7 × 215.9	5.5 × 8.5	1650 × 2550	US notepads, planners and half-sheet handouts.
127 × 203.2	5 × 8	1500 × 2400	Small US legal pads.
203.2 × 266.7	8 × 10.5	2400 × 3150	US school and government notepads.
431.8 × 558.8	17 × 22	5100 × 6600	Engineering drawings, four Letter sheets.
558.8 × 863.6	22 × 34	6600 × 10200	Engineering drawings, eight Letter sheets.
863.6 × 1117.6	34 × 44	10200 × 13200	Engineering drawings, sixteen Letter sheets.

A4 and Letter are not interchangeable. A4 is 5.9 mm narrower and 17.6 mm taller than Letter, so neither fits inside the other and a document laid out for one reflows on the other: usually a lost line at the foot of the page, or a blank page at the end. Set the page size in the document rather than scaling at the printer, and the reflow happens once, where you can see it. Nothing here is a printer margin. Every printer keeps a few millimetres of its own around the edge, and that unprintable area is not part of the paper size.

A6 in every unit

Computed from the defining dimensions, 105 by 148 mm, derived by ISO 216's halving rule from A0 at 841 by 1189 mm. Inches are the conversion at 25.4 mm to the inch; each pixel figure is the sheet in inches multiplied by that dpi and rounded to the whole pixel. Landscape is the same sheet turned. Printer margins are not part of a paper size and are not included.

Measurement	Portrait	Landscape
Millimetres	105 × 148 mm	148 × 105 mm
Centimetres	10.5 × 14.8 cm	14.8 × 10.5 cm
Inches	4.13 × 5.83 in	5.83 × 4.13 in
Pixels at 72 dpi	298 × 420 px	420 × 298 px
Pixels at 150 dpi	620 × 874 px	874 × 620 px
Pixels at 300 dpi	1240 × 1748 px	1748 × 1240 px

Common questions

What size is A6 paper?: 105 by 148 mm, which is 4.13 by 5.83 inches. The millimetres are the defining dimensions here: A6 comes out of ISO 216, which fixes A0 at 841 by 1189 mm and makes every size below it the one above halved across its long side and rounded down to the whole millimetre. The inches are the conversion.
Is A6 the same as a postcard or a 4 by 6 photo?: A6 is the standard postcard size in most of the world, so postcard and A6 usually mean the same thing. A 4 by 6 photo print is not the same: A6 is 3.4 mm wider and 4.4 mm shorter, so neither one fits inside the other. Printing an A6 design on 4 by 6 paper crops the sides or leaves a strip at one end.
How does A6 relate to A4 and A5?: Two A6 sheets side by side make A5, and folding A6 in half gives A7. A6 is a quarter of A4: fold A4 in half for A5 and in half again for A6, so four A6 cards come out of one A4 sheet, to within the millimetre ISO 216 rounds away at each halving.
How many pixels is A6 at 300 dpi?: 1240 by 1748 in portrait, and 620 by 874 at 150 dpi or 298 by 420 at 72 dpi. Because A6 is defined in millimetres, the inch dimensions are not round numbers and the pixel counts are rounded to the nearest whole pixel, so an A6 canvas at 300 dpi is 1240 pixels wide rather than exactly 1240.157.
Is A6 exactly 1 to root 2 like the other A sizes?: Almost. ISO 216 rounds each halving down to whole millimetres, which leaves A6 at 1 to 1.4095 rather than the ideal 1 to 1.4142. That is a real difference of about a third of a millimetre across the width, and it is why pages that print 1:1.414 against every size are stating something false about the small ones.

Dimensions follow ISO 216 and the ANSI/ASME standards exactly; pixel sizes are dimensions times the DPI named. Printers add their own margins, which are not part of a paper size.