How to Choose a Poster Size? A Comparison of 30x40, 50x70, and A3

How to choose a poster size? Start with one rule: the poster should occupy between half and two-thirds of the width of the furniture below it. In practice, this rule means: for a 180-220 cm sofa, a single 50×70 is too small, while two 50×70s or three 40×50s fit perfectly; for a 120-140 cm desk, a 30×40 or 40×50 is sufficient; bedside tables, shelves, and narrow walls are the place for 21×30. As for A3 (29.7×42 cm), it does not fit into a 30×40 frame, as it is 2 cm too long. In this guide, we explain standard poster sizes, which measurements fit which furniture, room-by-room recommendations, and price differences; examples are from our framed poster collection, all produced in four sizes.

What are the standard poster sizes?

In Turkey, four sizes have become standard for framed poster sales: 21×30, 30×40, 40×50, and 50×70 cm. Alasart Atelier posters are also produced in these four sizes. The difference between them is not just size, but the aspect ratio: 30×40 (3:4) is more square, while 50×70 (5:7) is longer; the framing may change slightly as the same design is scaled up. In the comparison on the cover, the four sizes of the Red Stairs and White Cloud Minimalist Poster are side by side; the smallest is the size of a book cover, while the largest is like a small window.

Size	Ratio	Paper equivalent	Suitable for
21×30 cm	7:10	Close to A4 (21×29.7)	Shelf, bedside table, filler piece in a gallery wall
30×40 cm	3:4	2 cm shorter, 3 mm wider than A3	Desk, entryway, narrow wall, duo-trio series
40×50 cm	4:5	Fits A3 with a mat	Beside the headboard, beside the TV, main piece in a trio series
50×70 cm	5:7	Almost identical to B2 (50×70.7)	Above the sofa (duo), headboard, large empty wall

3 things that determine poster size

1. Furniture width. Whether it's a sofa, bed, console, or desk: the total width of the poster (or group of posters) should be at least half the width of the furniture and should not exceed two-thirds. For a 200 cm sofa, the target is 100-130 cm; this means two 50×70s (108 cm) with an 8 cm gap between them, or three 40×50s (136 cm). In the layout above, the Meditation in Moonlight Japanese Zen Poster and the Red Stairs poster set as a 50×70 pair establish exactly this ratio.

2. Viewing distance. From where will you view the poster? A wall 3 meters away from the opposite sofa calls for a 50×70; a wall viewed from 60 cm away while sitting at a desk looks large even with a 30×40. Rule: about one-quarter of the viewing distance is a good starting point for the long side of the poster (3 m → 70 cm; 1.5 m → 40 cm).

3. Wall space. Measure the height and width of the empty wall; there should be at least 15-20 cm of breathing room around the poster. A narrow and high wall calls for a vertical 30×40 series, while a wide and low wall calls for a horizontally placed 50×70 duo. Our wall decor measurement guide is helpful for general measurement logic, and our article on sofa-back wall decoration helps with compositions above sofas.

Which poster size for each room?

Living room: 50×70 duo or 40×50 trio for above the sofa; vertical 30×40 for the narrow strip next to the TV unit. A single 50×70 is only enough on its own if placed above a console narrower than 140 cm; living room compositions are in our living room wall decoration article.

Kitchen and dining area: 30×40 for above the counter or next to cabinets, 40×50 above the dining table. Kitchen posters should be hung on a wall away from moisture and steam; landscape scenes like the Amalfi Lemon Window View Poster create a "window" effect in 40×50. More ideas are in our kitchen wall decor article.

Study room: 30×40 for above the desk, 21×30 next to the monitor. Since you are looking at the desk from 60 cm away, a large size is distracting; simple graphics like the Black and White Minimalist Bicycle Line Art Poster find their best scale at 30×40. See our study room wall decor guide for height and layout.

Bedroom: 50×70 duo or a single 50×70 + two 30×40s above the headboard of a double bed (160 cm); a single 40×50 for a single bed. 21×30 above the bedside table. Details are in our headboard wall decor article.

Entryway and hallway: vertical 30×40 series (3-4 pieces, 8 cm apart) on narrow walls; 40×50 above the console. Our hallway decoration article is for long corridors.

Teen room and student housing: for frequently changing tastes, 30×40 is the most economical and flexible size; a single 50×70 looks more "established" at the head of the bed. Hobby posters like the Retro Orange Racing Bicycle with Turquoise Handlebars Poster gain character at 40×50 in the study corner. Details in our teen room wall decor and student housing articles.

Which frame does an A3 or A4 poster fit?

This is the most confusing topic. According to the ISO 216 standard, an A3 sheet is 29.7×42 cm; it is 2 cm too long for a 30×40 frame, and too small for a 40×50 frame. If you have an A3 print, the correct solution is a 40×50 frame + a mat (about 4-5 cm of white space on the edges) or a frame with A3 dimensions. A4 (21×29.7), however, fits into a 21×30 frame, leaving only a 3 mm gap. Since Alasart posters arrive fully framed at the exact size, you do not need to make these calculations; our how to choose a poster frame article guides you on choosing the frame color.

How does the price change as the size increases?

Size	Framed poster price	Frame options
21×30 cm	549 TL	Black, white, natural wood
30×40 cm	749 TL	Black, white, natural wood
40×50 cm	949 TL	Black, white, natural wood
50×70 cm	1,349 TL	Black, white, natural wood

Prices include the frame, 300 g/m² matte print, and hanging hardware; VAT is included, and shipping is free throughout Turkey. The frame color does not change the price. A 50×70 duo setup above the sofa costs 2,698 TL, while a trio of 40×50s covers a wider area at 2,847 TL. You can see the current status of the discount tiers for over 2,000 TL in the cart on the product page.

5 common mistakes when choosing size

1. Single small piece. A single 30×40 above a large sofa looks "forgotten"; either increase the size or increase the quantity. 2. Deciding without measuring. Tape the poster size on the wall with masking tape and live with it for two days; it's the cheapest testing method. 3. Orientation error. Typography posters are often vertical, landscapes are closer to horizontal; vertical designs like the AURA Red Retro Typography Poster suit narrow walls, while landscapes suit wide walls. 4. Randomly mixing sizes. Use no more than two different sizes in a series and place the larger one in the center. 5. Hanging too high. The center of the poster should be at 145-150 cm from the floor; details are in our how to hang a poster and installation guide; for hanging without drilling in a rental home, see our renter's guide. You can take a look at the framed poster layout boards on Pinterest for examples of layouts where different sizes are used together.

Frequently asked questions

Which size poster should be hung above a sofa?

The width of the poster group should be between half and two-thirds of the sofa's width. For a 180-220 cm sofa, two 50×70s or three 40×50s; for a sofa or console narrower than 140 cm, a single 50×70 is sufficient.

Is a 50×70 poster big?

It is ideal for living rooms, headboards, and large walls; it is too big for above a desk and in narrow entryways. 50×70 is the correct scale for walls viewed from 3 meters away, while 30×40 is sufficient for walls viewed from 1.5 meters.

Does an A3 poster fit into a 30×40 frame?

It does not; A3 is 29.7×42 cm, which is 2 cm longer than a 30×40 frame. Use a 40×50 frame + mat, or an A3-sized frame. Since Alasart posters arrive fully framed at the exact size, this problem does not occur.

Where is a 30×40 poster hung?

It is the most flexible size for above a desk, in entryways, on narrow walls, next to kitchen cabinets, and as a duo-trio series on a gallery wall. On its own, it looks too small above a large sofa.

Is the poster size measured with or without the frame?

Product dimensions refer to the print area (paper size); the frame increases the outer dimension by a few cm on each side. When planning your wall, use the framed outer dimensions.

Can two different sizes be hung side-by-side?

Yes, they can; the rule is to place the larger piece in the center, use no more than two sizes, and keep the frame color consistent. Align the tops or centers of the pieces.