Poster sizes chart: standard sizes in cm and inches

Poster sizes come from three systems that overlap only by accident: American inches, the ISO A series in millimetres, and the round centimetre sizes used across much of Europe. This chart gives each common size in both centimetres and inches, says which shape it belongs to, and ends with which size suits which wall.

Poster sizes chart: US sizes in inches and centimetres

US sizes are named in inches. Read the shape column as well as the size: sizes that share a shape swap into each other’s frames, while sizes with different shapes need cropping or a mat.

The movie one-sheet, 27×40 in (68.6×101.6 cm), and 28×40 in stand apart. The one-sheet is a little wider than 2:3, so it does not drop into a 24×36 in frame. Look for a frame made for 27×40 in. Smaller sizes such as 4×6 in (10.2×15.2 cm), 5×7 in (12.7×17.8 cm) and US Letter at 8.5×11 in (21.6×27.9 cm) are print and paper sizes rather than posters, so they are left out of the table.

ISO A sizes and European centimetre sizes

Outside North America, posters are usually A sizes or round centimetre sizes. A sizes are set by ISO 216: each is half the area of the one above, and all share the ratio 1:√2, about 1:1.414. Our guide to A1, A2 and A3 explains the rule in full.

Centimetre sizes are rounder numbers, and they do not share a single shape.

Several US and centimetre sizes are the same shape and no more than about 1.5 cm apart: 8×10 in and 20×25 cm, 16×20 in and 40×50 cm, 18×24 in and 45×60 cm, 24×36 in and 60×90 cm. They are close, not identical, so check a frame against the exact size.

Which shape each poster size belongs to

• 2:3: 4×6, 8×12, 12×18, 16×24, 20×30 and 24×36 in; 30×45 and 60×90 cm.
• 3:4: 6×8, 9×12, 12×16 and 18×24 in; 30×40 and 45×60 cm.
• 4:5: 4×5, 8×10 and 16×20 in; 20×25 and 40×50 cm.
• 5:7: 5×7, 10×14 and 20×28 in; 50×70 cm.
• ISO A: A5 to A0, all 1:1.414.

A print only fits a frame of the same shape without cropping or a mat. A1 (59.4×84.1 cm) can look close to 24×36 in (61×91.4 cm) in a listing, but A1 is 1:1.414 and 24×36 is 1:1.5, so the 24×36 is 1.6 cm wider and 7.3 cm taller. Our 24×36 vs A1 comparison goes through it.

Sizes are written width × height for a portrait print. Turn the print on its side and nothing about the shape changes: a 60×90 cm print hung in landscape is 90 cm wide and 60 cm tall.

Which poster size suits which wall

One rule of thumb covers any wall with furniture below it: the art, alone or as a group, should be about two-thirds of the furniture width.

• Small hallway: A3 (29.7×42 cm) or 30×40 cm. Hallways are seen close up and in passing, so a smaller print does not look lost. On a longer wall, a pair of 40×50 cm prints works.
• Desk or shelf: 8×10 in (20×25 cm) up to 11×14 in (27×35 cm), or A4. Small enough to lean on a shelf or hang beside a monitor.
• Above a sofa: apply the two-thirds rule. For a sofa 200 cm wide, aim for about 130 cm of art. A pair of 60×90 cm prints with a 5 cm gap is 125 cm wide; a pair of 70×100 cm prints is 145 cm. Our guide to art above a sofa goes further.
• A wide feature wall: one large print does the work of a group. A single 70×100 cm print hung in landscape is 100 cm wide, which is two-thirds of a cabinet or console 150 cm wide.
• Above a bed: use the width of the headboard. If it is 160 cm wide, two-thirds is about 105 cm, which is exactly what a pair of 50×70 cm prints with a 5 cm gap comes to.

Printing a poster size locally

Most prints at Montclair also come as an $8 Print Ready Package: seven print-ready files that cover 4×6 in to 24×36 in and A4 to A1, a guide to printing them, and a personal-use licence. It suits anyone who would rather have a local shop print at a chosen size and on a chosen paper.

Resolution is simple arithmetic: pixels equal inches multiplied by pixels per inch (ppi). At 300 ppi, the print-shop ideal, a 24×36 in poster needs 7200×10800 px. Around 150 ppi, which is 3600×5400 px at the same size, still looks sharp from a metre or more.

Sizes at Montclair

Montclair prints are made to order on 200gsm archival matte paper with pigment inks, framed or unframed. Frames come in black, white, natural wood or dark wood and arrive ready to hang. Unframed prints ship rolled in a protective tube, with free tracked shipping worldwide. Sizes include 30×40, 45×60, 60×90 and 70×100 cm, and A3 to A0. Browse the classic cars collection, or open a print such as Ayrton Senna at Monaco, and choose a size on the product page.