What are the standard poster sizes in the US?
US poster printing is built around a handful of inch formats. Small sizes suit counters, notice boards and doors. Medium sizes suit hallways and shop walls. Large sizes suit lobbies, event entrances and any place where people read from across a room.
| Size (inches) | Millimeters | Aspect ratio | Pixels at 300 PPI | Pixels at 150 PPI |
|---|---|---|---|---|
| 11 × 14 | 279 × 356 | 11:14 | 3,300 × 4,200 | 1,650 × 2,100 |
| 11 × 17 | 279 × 432 | 11:17 | 3,300 × 5,100 | 1,650 × 2,550 |
| 12 × 18 | 305 × 457 | 2:3 | 3,600 × 5,400 | 1,800 × 2,700 |
| 18 × 24 | 457 × 610 | 3:4 | 5,400 × 7,200 | 2,700 × 3,600 |
| 24 × 36 | 610 × 914 | 2:3 | 7,200 × 10,800 | 3,600 × 5,400 |
The pixel columns exclude bleed. For large posters viewed from a few feet away, 150 PPI at the finished size is often acceptable; 300 PPI suits pieces that people inspect up close.
What are the ISO A series poster sizes?
Outside North America, posters usually follow ISO 216. Every A size has an aspect ratio of the square root of two, about 1 to 1.414, so halving a sheet produces the next size down with the same proportions. That makes it easy to scale one design across several sizes without a new crop.
A4 is 210 × 297 mm, A3 is 297 × 420 mm, A2 is 420 × 594 mm, A1 is 594 × 841 mm and A0 is 841 × 1189 mm. An A2 poster, about 16.5 × 23.4 inches, is close to 18 × 24, and A1, about 23.4 × 33.1 inches, is close to 24 × 36, but the shapes differ, so artwork moved between the two systems needs a layout check.
How do you choose the right poster size?
Work from the wall, not the file. Measure the visible opening of the frame, holder or wall space, then note where people stand when they first notice the poster. A useful benchmark is the ADA Standards for visual characters on signs: text viewed from 72 inches or more should be at least 5/8 inch tall plus 1/8 inch for every foot of viewing distance beyond 72 inches, when the text sits between 40 and 70 inches above the floor. Promotional posters are not bound by that rule, but it is a sensible floor for headline legibility.
If your headline must work from 15 feet, that benchmark suggests capital letters at least 1.75 inches tall. Fitting a headline that size plus an image and a call to action usually points to 18 × 24 or larger. Once you know the approach distance, planning a 24 x 36 poster shows how to use the largest format without filling it with copy.
Why does aspect ratio matter when you resize a poster?
Sizes that look similar can have very different shapes. A 24 × 36 poster is 2:3, while 18 × 24 is 3:4. Moving a 24 × 36 design into an 18 × 24 frame means cropping the long side or adding borders. The comparison of 11 x 17 versus 18 x 24 walks through that tradeoff for two of the most popular sizes.
Before resizing, mark the subject of every photograph and the position of the headline. If either lands near the edge after a crop, redesign the layout rather than simply scaling it.
How much resolution does a poster file need?
Divide the pixel width of your image by the printed width in inches to find the effective PPI. A photo 3,600 pixels wide printed 24 inches wide delivers 150 PPI. Changing the PPI number in software without adding pixels does not add detail. For a size by size breakdown and upscaling advice, see the poster resolution guide.
Do you need bleed on a poster?
Yes, whenever color or an image runs to the edge. The printer trims through the bleed, so a small extension on every side prevents white slivers. Enter the finished size and bleed in a bleed calculator to get the exact artwork dimensions and pixel targets for the template you are using. Keep text well inside the trim, especially if a frame will cover the edges.
Which sizes fit standard frames and holders?
Frames are sold by the poster size they hold, but the visible opening is usually smaller than the sheet because the frame lip covers part of the edge. Measure that lip before placing text near the border. A snap frame lets you swap posters without taking the frame off the wall, which helps when promotions change often.
What should your final poster specification include?
Write down every decision before ordering, so a later change becomes deliberate.
- Finished width × height and orientation
- Bleed amount and safe margin from the template
- Effective PPI of the most demanding image
- Paper stock, finish and any lamination
- Mounting method: frame, rails, adhesive or pins
- Indoor or outdoor exposure
- Quantity per design and the delivery date
Poster sizes also affect handling. Large posters ship rolled or flat in bigger packaging, need more wall space during installation and often require two people to hang straight. If a location is hard to reach or changes often, a smaller poster at eye level can outperform a larger one placed high, because more people actually read it. Choose the size that suits the space and the audience, not simply the biggest one available.
Custom posters are available in eight sizes from 11 × 14 up to 24 × 36 inches, in portrait or landscape, starting at $4.99 for a single print.
Frequently asked questions
What is the most common poster size?
In the US, 18 × 24 and 24 × 36 inches are among the most widely used display sizes, with 11 × 17 common for notice boards and counters. Internationally, A2 and A1 from the ISO 216 series fill similar roles. Pick the size from the wall space and reading distance rather than habit, and check that your artwork's aspect ratio matches.
Is 18 × 24 the same shape as 24 × 36?
No. An 18 × 24 poster has a 3:4 aspect ratio, while 24 × 36 is 2:3, which is proportionally longer. Artwork made for one will need cropping, borders or a revised layout to fill the other. Mark the subject of each photograph and the headline position before resizing so nothing important lands near a trimmed edge.
How big should poster text be?
Size text from viewing distance. The ADA Standards for sign characters call for at least 5/8 inch at up to 6 feet, plus 1/8 inch for each additional foot. At 15 feet that is about 1.75 inches for capital letters. Promotional posters are not required to meet that rule, but it is a practical minimum for headlines.
What resolution does a 24 × 36 poster need?
At 300 PPI, a 24 × 36 inch poster needs 7,200 × 10,800 pixels before bleed. At 150 PPI, often acceptable for large posters read from a few feet away, it needs 3,600 × 5,400 pixels. Start from the largest original image available, because raising the PPI setting in software does not create real detail.
Sources & specification notes
The references below support the relevant technical or product details in this guide. Examples and checklists are not claims of practical testing or universal supplier requirements. Confirm the current specifications for your chosen product before production.
- U.S. Access Board: ADA Standards, 703.5.5 visual character height ↗
Table 703.5.5 sets minimum sign character height by viewing distance; used here as a legibility benchmark.
- University of Cambridge (Markus Kuhn): ISO 216 paper sizes ↗
Reference summary of the ISO 216 A and B series dimensions and the square root of two ratio.
