--- title: Poster sizes in cm and inches description: Every exact 2:3 poster size in centimetres and inches, which one to choose for which wall, and why printing a 2:3 image on A4 or A3 leaves white borders. canonical: https://paperanniversarygift.com/print-guide/poster-sizes/ last-updated: 2026-09-09 --- # Poster sizes in cm and inches > The exact 2:3 sizes are 20×30, 30×45, 40×60, 50×75 and 60×90 cm (8×12, 12×18, 16×24, 20×30 and 24×36 inches). 30 × 45 cm is the one most people choose. A-series paper (A4–A1) is a 1:√2 ratio, so a 2:3 image prints on it with thin white borders down the left and right. Every exact 2:3 poster size in centimetres and inches, which one to choose for which wall, and why printing a 2:3 image on A4 or A3 leaves white borders. Source: https://paperanniversarygift.com/print-guide/poster-sizes/ Published: 2026-09-09 | Updated: 2026-09-09 --- ## The exact sizes These crop nothing. Any 2:3 file scales to all of them. | Centimetres | Inches | Best for | | --- | --- | --- | | 20 × 30 cm | 8 × 12 in | A desk, a shelf, a bedside table | | 30 × 45 cm | 12 × 18 in | **The default.** Standard frame size, labels readable across a room | | 40 × 60 cm | 16 × 24 in | Above a bed or a sofa | | 50 × 75 cm | 20 × 30 in | Gallery scale, or anything guests will read up close | | 60 × 90 cm | 24 × 36 in | A print-shop order, and a statement wall | ## How to choose **Measure the wall, not the frame.** A print should occupy roughly two-thirds to three-quarters of the width of the furniture beneath it. Above a standard sofa that means 50 × 75 cm; above a bedside table, 30 × 45. **Then think about the labels.** A map with eight labelled stops is dense. At 20 × 30 cm the smallest place names are legible up close and not from a sofa. At 30 × 45 they read from a couple of metres. At 50 × 75 they read across a room, which is what you want if anyone other than you will look at it. **When in doubt, go one size up.** Almost nobody regrets a print being slightly too large; a great many people regret one being slightly too small. ## Why A4, A3, A2 and A1 leave borders A-series paper uses a ratio of 1:√2, about 1:1.414. A 2:3 image is 1:1.5. The two do not match, so when a 2:3 image is fitted to the height of A-series paper, some paper is left over on each side. | A size | Millimetres | Border each side with a 2:3 image | | --- | --- | --- | | A4 | 210 × 297 mm | ~6 mm | | A3 | 297 × 420 mm | ~9 mm | | A2 | 420 × 594 mm | ~12 mm | | A1 | 594 × 841 mm | ~17 mm | These are small. Three ways to handle them: 1. **Leave them.** Inside a frame they read as a deliberate margin. 2. **Trim them** with a guillotine or a steel rule and a sharp blade. 3. **Use a mount** cut to the artwork, which hides the borders and looks better than either option. Printing at home on A4 or A3 is completely fine. The border is a footnote, not a problem. ## US paper sizes US Letter (8.5 × 11 in) is roughly 1:1.29, which is squarer than A4, so a 2:3 image leaves slightly wider side borders. If you are printing at home in the US and want no borders, ask a print shop for 8 × 12 in instead. It is an exact 2:3 and costs very little. ## What "300 DPI" means for size The file is 300 DPI, which means it holds enough detail to print at the largest size on this page without softening. You cannot make a file sharper by printing it smaller, and you cannot run out of resolution before 60 × 90 cm. If a printer asks you to confirm the resolution, the answer is 300 DPI and the colour profile is sRGB. ## Frames in these sizes 30 × 45 cm and 50 × 75 cm are standard across European frame ranges and poster specialists like Desenio and Posterstore. In the US, 12 × 18 in and 24 × 36 in are the common ones. [Frame styles](/print-guide/frame-styles/) covers which suits the artwork. ## Buying the frame before you have the file The most common mistake is doing it in that order: buying a 50 × 70 cm frame, then finding out the file is 2:3 and 50 × 70 is not. 50 × 75 is. Check the ratio, then pick the size, then buy the frame. If you are reading this because you are about to order a print-at-home poster as a gift, the [custom love map](/custom-love-map/) is one of these: a 300 DPI PDF in a 2:3 ratio, so every size in the table above fits it without cropping. For what else is worth considering alongside it, there are gift guides for [a girlfriend](/anniversary-gifts-for-girlfriend/), [a boyfriend](/anniversary-gifts-for-boyfriend/), [a husband](/paper-anniversary-gifts-for-husband/) and [a wife](/paper-anniversary-gifts-for-wife/).