Art Print Sizes in Inches and Centimetres: A4, A3, 8×10 and More

An A4 print is 21.0 × 29.7 cm, an A3 print is 29.7 × 42.0 cm, and an 8 × 10 inch print is 20.32 × 25.40 cm. But those numbers are only useful after you know what was measured. A seller may be describing the paper, the printed image, the opening in a mat—a board that surrounds a work on paper—or the frame’s nominal size. These are related dimensions, not interchangeable ones.

Common art print sizes

The centimetre conversions below use the exact relationship 1 inch = 2.54 cm, documented in the US National Institute of Standards and Technology’s conversion factors. Converted figures are shown to two decimal places.

An aspect ratio is the relationship between width and height. The table expresses it as short side to long side, so the ratio stays the same when a print turns from portrait to landscape.

Named size	Inches	Centimetres	Shape, or aspect ratio
A4	8.27 × 11.69 in	21.0 × 29.7 cm	1:√2, about 1:1.414
A3	11.69 × 16.54 in	29.7 × 42.0 cm	1:√2, about 1:1.414
8 × 10	8 × 10 in	20.32 × 25.40 cm	4:5
11 × 14	11 × 14 in	27.94 × 35.56 cm	11:14
12 × 18	12 × 18 in	30.48 × 45.72 cm	2:3
16 × 20	16 × 20 in	40.64 × 50.80 cm	4:5
18 × 24	18 × 24 in	45.72 × 60.96 cm	3:4
24 × 36	24 × 36 in	60.96 × 91.44 cm	2:3

The A-series belongs to the international paper-size system covered by ISO 216. It is designed around a 1:√2 proportion, so cutting a sheet in half along its long side produces the next size with nearly the same shape: A3 becomes two A4 sheets. Published sizes use whole millimetres, so use the standard dimensions rather than recalculating them from the irrational ratio. ISO also notes that the standard does not necessarily apply to posters and other special items. A public A-size table from Hampshire County Council confirms the dimensions in millimetres.

A-series sheet	Exact dimensions in millimetres	Centimetres
A0	841 × 1189 mm	84.1 × 118.9 cm
A1	594 × 841 mm	59.4 × 84.1 cm
A2	420 × 594 mm	42.0 × 59.4 cm
A3	297 × 420 mm	29.7 × 42.0 cm
A4	210 × 297 mm	21.0 × 29.7 cm
A5	148 × 210 mm	14.8 × 21.0 cm
A6	105 × 148 mm	10.5 × 14.8 cm

A0–A5 dimensions are listed by Hampshire County Council; A6 is also documented in Epson’s paper specifications. These standard sheet names do not guarantee that a particular artwork or frame is sold in all seven sizes.

Sizes such as 8 × 10 and 11 × 14 come from inch-based conventions. They do not share one common shape. That is why changing size can change composition even when neither number looks dramatically different.

The table is a measurement reference, not a claim that GeMarkt—or any one seller—offers every size. Check the individual listing.

Paper size is not always image size

Before choosing a frame, identify four measurements:

• Paper size is the full edge-to-edge sheet.
• Image size is the area carrying the picture. A white border may sit between the image and the paper edge.
• Mat size has both an outside dimension and a window opening. The window is normally slightly smaller than the paper or image it holds, so the work does not fall through it.
• Frame size often names the item it is intended to hold, not the frame’s outside edge. The border around the picture makes the outside dimension larger.

For example, an A4 sheet is 210 × 297 mm. If an image is printed with a 20 mm border on every side, the image itself is 170 × 257 mm—about 6.69 × 10.12 inches—while the paper remains A4. Ordering a frame from the image dimensions would ignore the border; ordering one from the paper dimensions without checking the mat could hide more of the sheet than intended. As the UK National Archives’ print-ready guide illustrates, the trimmed size is the sheet after its final cut, while artwork intended to bleed normally extends beyond the trim before cutting. A full-bleed image reaches the finished edge; it is not a white border.

The Canadian Conservation Institute’s guidance on matting works on paper separates the window mat, back mat and object, and explains why the window overlaps the work. Its companion note on framing works on paper treats the frame as a protective system rather than just an outside measurement.

Why A4 and eight by ten are not substitutes

A4 and 8 × 10 are close in overall area, but their proportions differ. In portrait orientation, A4 is taller and narrower. An 8 × 10 rectangle has a width-to-height ratio of 0.8; A4 is about 0.707.

If you put an A4-proportioned image into an 8 × 10 opening without distortion, you have two choices. You can show the whole image and accept extra space at the sides, or enlarge it until the opening is filled and crop part of the top and bottom. Stretching the picture to fit is a third technical possibility, but it changes the shapes inside the art and is rarely a neutral choice.

The same issue appears with photographs and digital files. Imagine a 6000 × 4000 pixel photograph, which has a 3:2 ratio. It fits a 12 × 18 inch print exactly in proportion. To fill a 10 × 8 inch landscape print, whose ratio is 5:4, the image can be cropped to 5000 × 4000 pixels. That removes 1000 pixels of width in total—about 16.7% of the original width—500 pixels from each side if the crop is centred. Fitting the complete image instead makes it 10 × 6.67 inches on that sheet, leaving roughly 0.67 inch (16.93 mm) above and below. A face or signature near an edge could disappear.

Adobe’s documentation distinguishes resizing and resampling from setting a crop ratio with the Crop tool. Cropping changes which part of the image remains. Resampling changes the number of pixels. Neither should happen invisibly when you order a different shape.

What size should you order for an existing frame?

Open the frame and measure the space that actually receives the protective glass or acrylic, mat and backing. Then check the frame maker’s stated size. A frame sold as 8 × 10 may be intended for an 8 × 10 sheet, or it may include a mat whose opening is smaller. The outside edge will be larger in either case.

That receiving recess is called the rebate, or rabbet. Measure at the back, not across the smaller opening visible from the front. Confirm both the fitting dimensions and the available depth: an 11 × 14 inch mat needs a frame intended for that package, with the maker’s fitting allowance. An outside measurement such as 13 × 16 inches tells you the footprint on the wall, not what will fit inside.

If a mat is already present, record at least three dimensions:

1. the frame’s stated or internal fitting size;
2. the mat’s outside size;
3. the visible window opening.

One 8 × 10 inch image can produce several measurements. Suppose it is centred on an 11 × 14 inch sheet. That leaves 1.5 inches of paper at each side and 2 inches at top and bottom. A 7.5 × 9.5 inch mat window would then overlap the image by 0.25 inch on every edge, while the mat’s outside remains 11 × 14. The frame must accept that package, but its outside footprint will be larger and depends on the frame border. If the covered quarter-inch contains important detail, choose a larger window, add a border to the print or use a mounting design assessed for the particular work.

A practical ordering checklist

Use this sequence before you buy:

1. Read the listing’s definition of size. Is it paper, image or framed outside size?
2. Write both units. Convert inches to centimetres by multiplying by 2.54; convert centimetres to inches by dividing by 2.54.
3. Compare aspect ratios. Matching the ratio avoids cropping, though a border can let a different ratio sit on the same sheet.
4. Ask whether the image is cropped. A preview should show the actual composition, not merely a generic room mock-up.
5. Record any border. Note its width and whether it is included in the advertised dimensions.
6. Measure the mat window and overlap. Do not assume that an 8 × 10 mat exposes the full 8 × 10 inches.
7. Check the frame’s internal and external dimensions. The nominal size alone cannot tell you the final footprint.

Once the flat dimensions are settled, choose whether the work should arrive as paper, canvas or a framed object in the print format guide. For deciding how large the finished piece should feel on a particular wall, use the separate wall-size guide. This guide answers the earlier question: what, exactly, do the numbers on the print mean?

Quick answers

Is A4 the same as 8 × 10 inches?

No. A4 is about 8.27 × 11.69 inches and is taller in proportion. An 8 × 10 print is 20.32 × 25.40 cm and has a 4:5 ratio.

Is 12 × 18 the same shape as 24 × 36?

Yes. Both have a 2:3 ratio, so an image can scale between them without cropping if the printable area and border treatment also scale as intended.

Does the listed print size include the white border?

Sometimes, but not always. The listing must say whether it gives the sheet size or image size. Ask for both when the wording is unclear.