Standard Poster Sizes and How to Make One With AI

The standard poster size depends on where you are printing. In most of the world it is the ISO A series — A4, A3, A2, A1 and A0 — while US print shops work in inches, with 18 × 24 in and 24 × 36 in as the two most common wall sizes. For a poster you will hand out, pick A4 or A5; for a wall poster, A2 or 18 × 24 in is the safe default because almost every frame and print service supports it.

Updated October 2026.

What “standard” actually means

There is no single global poster size, because two measurement systems are in everyday use. The ISO 216 A series is used in most countries: each size is half the area of the one before it, and every sheet keeps the same 1:1.414 shape. That is why a poster designed at A2 scales down to A3 without cropping — the proportions never change.

US print shops use inches and a set of trade sizes that grew up separately from the A series. They do not share the A series ratio, so an 18 × 24 in poster is squarer than A2 even though the two are close in area. If you are printing in the United States, ask for the inch size; everywhere else, ask for an A size. Sending an A2 file to a shop that expects 18 × 24 in will either letterbox it or shave the edges.

ISO A series poster sizes

These are the sizes to quote in millimetres or inches. The pixel column is the file size you need for a sharp print at 300 DPI, which is the usual standard for anything read up close.

Size	Millimetres	Inches	Pixels at 300 DPI	Typical use
A5	148 × 210 mm	5.8 × 8.3 in	1748 × 2480	Leaflets, small notices
A4	210 × 297 mm	8.3 × 11.7 in	2480 × 3508	Flyers and desk posters
A3	297 × 420 mm	11.7 × 16.5 in	3508 × 4961	Window and small wall posters
A2	420 × 594 mm	16.5 × 23.4 in	4961 × 7016	The default wall poster
A1	594 × 841 mm	23.4 × 33.1 in	7016 × 9933	Large wall posters
A0	841 × 1189 mm	33.1 × 46.8 in	9933 × 14043	Event backdrops, big retail

Large-format printers rarely need 300 DPI. A wall poster read from a metre away is normally printed at 150 DPI, which halves the pixel count — an A1 needs roughly 3508 × 4966 pixels rather than the figure above. Ask your print shop which resolution they want before you upscale anything.

US poster sizes in inches

These are the sizes US shops quote most often. They are all portrait measurements; rotate them for landscape.

Size	Millimetres	Pixels at 300 DPI	Pixels at 150 DPI
8.5 × 11 in	216 × 279 mm	2550 × 3300	1275 × 1650
11 × 17 in	279 × 432 mm	3300 × 5100	1650 × 2550
18 × 24 in	457 × 610 mm	5400 × 7200	2700 × 3600
24 × 36 in	610 × 914 mm	7200 × 10800	3600 × 5400

How to choose a size in one minute

Handed to someone: A4 or A5. Both fit a bag and print on any office machine.
On a wall, read from a metre away: A2 or 18 × 24 in. Frames this size are cheap and everywhere.
Read from across a room: A1 or bigger, and cut your text to a headline plus one line.
Posted online only: ignore print sizes and match the platform instead — 1080 × 1350 for a vertical feed post, 1080 × 1920 for a story.
Being sold as a print: stick to the family of sizes your buyer will frame, usually the A series or 18 × 24 in.

How to make one with AI on VdoBloom

The poster, flyer and menu maker builds the whole layout from your text rather than starting from a template. You fill in a short form, and the tool lays the design out around the words you typed.

Open the tool and pick a Design type: event flyer, restaurant menu, sale poster or travel poster. This decides the underlying layout logic.
Type the headline. It is printed exactly as you write it, up to 80 characters, so spell it the way you want it to appear.
Add the rest of the text, one line each. Date, time, address, price, website, a short line of copy — each line is printed exactly as typed, up to 20 lines and 900 characters in total.
Choose a style: modern bold, elegant, retro, playful or luxury dark.
Name your colours if you want control beyond the style preset — for example navy, gold and cream. Leaving this blank lets the style decide.
Pick a shape. The tool offers 3:4, 2:3, 9:16, 1:1 and 4:3. Match the shape to your print size: 2:3 is the closest to A-series proportions, 3:4 suits flyers and handbills, 9:16 is for phone screens, 1:1 for square posts and 4:3 for landscape.
Generate. The layout comes back as a finished image in a minute or two, and the exact credit cost is shown on the button before you press it.

One honest limit: the tool works in shapes, not in paper sizes. You pick 2:3 and then tell your print shop you want A2, or you paste the 2:3 file into a 2:3 canvas at your exact pixel dimensions. A 2:3 print at 24 × 36 in is an exact match, which is why that combination is the easiest to send straight to a printer.

Prompt and text examples

Because the headline and body lines are printed literally, write them as you would for a designer rather than as a prompt.

Event flyer. Headline: “Summer Night Market”. Lines: “Saturday 14 June · 6–11 pm”, “Riverside Park”, “Free entry”, “Live music & 40 stalls”. Style: modern bold. Colours: deep green, cream.
Restaurant menu. Headline: the restaurant name. Lines: each section and dish on its own line. Style: elegant. Shape: 3:4.
Sale poster. Headline: “Half price, three days only”. Lines: dates, store address, the exclusions. Style: retro. Colour: red and cream.
Travel poster. Headline: the place name. Lines: one line of mood copy and a call to action. Style: playful or luxury dark depending on the destination.

Common mistakes

Designing at the wrong shape. A 1:1 poster cannot become A2 without either cropping or white bars. Decide the print size first, then the shape.
Too much text on a big sheet. The larger the poster, the fewer words it should carry. A0 with 20 lines is unreadable from any distance.
Forgetting the text is literal. Every line is printed exactly. Typos, missing hyphens and stray spaces all survive into the output.
Not leaving a margin. Keep text away from the outer edge so a trim does not cut into it. If your printer wants bleed, ask them for the margin figure before you generate.
Printing a phone-shaped file. A 9:16 poster is for screens. Printed at A2 it wastes most of the sheet.

Whatever shape and model you choose, the credit cost is displayed before the generation runs, and paid plans produce watermark-free output with commercial rights. See the plans if you are working out how many posters your monthly credits cover.

Frequently asked questions

What is the most common poster size?

For wall posters, A2 (420 × 594 mm) in countries that use the metric system and 18 × 24 in in the United States. For posters handed to people, A4. Those three cover the large majority of retail print jobs, which is why frames, sleeves and print-shop price lists are built around them.

What pixel size should a poster be?

Multiply the inches by the DPI your printer asks for. At 300 DPI an A2 is 4961 × 7016 pixels and an 18 × 24 in poster is 5400 × 7200 pixels. For large-format printing that is viewed from a distance, 150 DPI is normal and halves those numbers.

Is A2 bigger than 18 × 24?

They are close but not identical, and they are not the same shape. A2 is 420 × 594 mm, about 16.5 × 23.4 in. An 18 × 24 in poster is slightly larger and squarer. Keep the two separate and always confirm the units with your print shop.

Can I make a poster without design software?

Yes. The poster maker generates the entire layout from a headline, a list of text lines, a style and a colour direction, so you never open a canvas or move a text box. You can also see the full list of formats and other poster sizes the tool supports before you start.

Why does the AI sometimes spell my text wrong?

Image models render lettering as pixels rather than as editable type, so unusual words and long strings are where errors appear. Keeping headlines short, avoiding all-caps runs and spelling brand names plainly all help. Our guides on why AI misses text and the models that handle text best go further into this.

Ready to make yours? Open the AI poster and flyer maker, type your headline and text lines, choose a shape that matches your print size, and generate — the cost is shown before you run it.