Buyer guide

A4, A3 and A2 paper sizes in mm and inches for frame briefs

A4, A3 and A2 are defined in whole millimetres by the A-series paper system. The inch figures you see beside them are conversions that guides print in different forms. This guide shows where the sizes come from and how to use them in a frame brief.

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Short answer

The short answer

A4 is 210 x 297 mm, A3 is 297 x 420 mm and A2 is 420 x 594 mm [1][3]. They come from A0, which has an area of one square metre, and each step halves the sheet while keeping a height-to-width ratio of the square root of two [1]. Inch values such as 8.3 x 11.7 are not part of the standard, and guides print them differently [1][2], so quote millimetres in any purchase order.

By the ArtzFolio manufacturing team.

The three sizes in millimetres

The A-series sizes are defined in millimetres. Markus Kuhn of the University of Cambridge Computer Laboratory lists A4 as 210 x 297, A3 as 297 x 420 and A2 as 420 x 594 [1]. The University of Melbourne Print Room page and the Paper Sizes reference give the same figures [2][3].

Width comes first in these figures and height second, so each size is shown upright (portrait). Turn the sheet on its side and you have landscape. A frame for the same sheet works either way, so state the orientation in your brief.

Kuhn traces the series to the German standard DIN 476 of 1922 and lists ISO 216:1975 as the international standard [1]. The table below sets the three sizes beside the inch values commonly printed.

A4, A3 and A2: millimetres and inch values as commonly printed
Size	Millimetres (width x height)	Inches, decimal [2]	Inches, unofficial fractions
A4	210 x 297 [1][3]	8.3 x 11.7 [2]	8 1/4 x 11 3/4 [1]
A3	297 x 420 [1][3]	11.7 x 16.5 [2]	11 3/4 x 16 1/2 [1]
A2	420 x 594 [1][3]	16.5 x 23.4 [2]	16 1/2 x 23 3/8 [1]

Only the millimetre column is the standard. The inch columns come from different guides and differ [1][2].

How the A-series is derived

The system rests on three rules, all stated by Kuhn [1].

Figure: A2, A3 and A4 drawn at half scale to show the halving rule in the guide. Millimetres are the standard; inch figures are only labels.

A0 has an area of one square metre.
The height-to-width ratio of every sheet is the square root of two, about 1.4142 to 1.
Cut any sheet in half parallel to its shorter side and you get the next size down, so A2 gives A3 and A3 gives A4 [1].

Because of the root-two ratio, a half-sheet keeps the same proportions as the full sheet [1]. You can see the halving in the standard sizes: A2 at 420 x 594 mm has a short side of 420 mm, which is the long side of A3 at 297 x 420 mm [1][3].

Published figures are whole millimetres. Paper Sizes says they are rounded to the nearest millimetre [2], while Kuhn describes rounding down to the next lower whole millimetre during halving [1]. ISO 216 allows tolerances of +/-2 mm for dimensions above 150 mm up to 600 mm [1].

Why inch figures are only a label

The ISO paper sizes are based on the metric system [1]. Any inch figure beside A4, A3 or A2 is a conversion, and guides print them in different forms [1][2]. Kuhn describes his fractions as unofficial and tells product designers to use the official millimetre values [1].

Paper Sizes prints A4 as 8.3 x 11.7 in, A3 as 11.7 x 16.5 in and A2 as 16.5 x 23.4 in [2].
Kuhn's unofficial table uses fractions instead, such as 8 1/4 x 11 3/4 in for A4, 11 3/4 x 16 1/2 in for A3 and 16 1/2 x 23 3/8 in for A2 [1].

Kuhn says each fraction uses the smallest denominator that stays within the ISO 216 tolerance limits [1]. Paper Sizes does not say how its inch values were derived [2].

If one supplier writes 8.3 x 11.7 and another writes 8 1/4 x 11 3/4, they may both mean A4 [1][2]. Put the millimetre size in your order and treat any inch figure as a label, not a specification.

What the BIS listing tells you

In India, the Bureau of Indian Standards (BIS) lists IS 1064:1980, titled "Specification for paper" (Second Revision), under the aspect "Dimensions" [4]. The listing page shows no scope text, and it gives the degree of equivalence as "Not Equivalent" [4]. So this guide does not claim that IS 1064 is the same document as ISO 216.

The A-series millimetre sizes are given by the University of Cambridge and University of Melbourne pages [1][3]. For the wider picture of frame and paper sizes in India, see the pillar guide, standard photo frame and paper sizes in India.

Using the sizes in a frame brief

A paper size is the size of the sheet, not the size of a finished frame. The frame opening, any mount and the moulding width all change the outer size, so a frame brief needs more than the paper name. See photo frame profiles: fine, slim, classic and broad for the profile options.

When you write a brief, give these points.

The paper size name and its millimetre dimensions, for example A3, 297 x 420 mm [1][3].
Portrait or landscape.
Whether the print sits behind a mount, and the visible opening you want, so the supplier can confirm the frame size against your brief.
Which profile and glazing you want.

Example brief line: "A3 portrait, 297 x 420 mm, visible opening to be agreed" [1][3]. Our guide to briefing a frame or board order covers the full list. If you are planning a range, how to start a photo frame brand in India shows where size choices fit.

How this applies when you work with us

ArtzFolio is a private-label and OEM/ODM manufacturer in Noida, serving businesses and brands only. Minimum order and lead time are confirmed in our quote. Samples are paid, and the cost may be reimbursed or adjusted by agreement. Our shipping term is EXW Noida, and payment is 50% advance, with the balance as agreed. We reply to enquiries within 1 business day. Send your brief through our contact page, or see pricing, minimums and lead times for how quotes work.

Questions buyers ask

What are the dimensions of A4, A3 and A2 in mm?

Quote A4 as 210 x 297 mm, A3 as 297 x 420 mm and A2 as 420 x 594 mm, width first and height second [1][3]. The University of Cambridge and University of Melbourne pages give the same figures, which is why millimetres are the safe unit to write into a frame order.

Why does every A size keep the same proportions?

Because the ratio is the square root of two, a half-size sheet is a smaller copy of the full sheet. Halving parallel to the shorter side gives the next size with the same ratio [1].

Should I write A3 or 297 x 420 mm in a frame order, and are inch sizes official?

Write both, with the millimetre size taking precedence. Inch sizes are not official: ISO 216 is metric, and A4 appears as 8.3 x 11.7 in in one guide and as 8 1/4 x 11 3/4 in in another [1][2].

Is IS 1064 the Indian version of ISO 216?

This guide cannot say so. The BIS listing for IS 1064:1980 shows the title "Specification for paper" and gives the degree of equivalence as "Not Equivalent" [4].

Is an A3 frame the same size as an A3 print?

No. The paper size is the sheet, not the finished frame. State whether the print sits behind a mount and the visible opening you want, and give the millimetre size and profile in your brief.