18x24" Poster Print Quality Checker
Standard medium poster size: 18 × 24 inches (457 × 610 mm). High quality 300 DPI requires 5400 × 7200 pixels.
At 300 DPI (Gallery Sharp): Minimum 5400 × 7200 pixels.
At 150 DPI (Poster Viewing): Minimum 2700 × 3600 pixels.
18×24" Print Guide
Everything you need to print 18x24" Poster sharp
The 18 × 24 inch poster (46 × 61 cm) is a popular size for art prints, event posters, film posters and shop displays. Its 3:4 shape matches phone photos exactly, so they print without cropping.
At 300 DPI it needs 5400 × 7200 pixels, almost 39 megapixels, which few cameras produce. But posters are viewed from a metre or more, where 150 DPI (2700 × 3600 pixels) looks sharp and 200 DPI is plenty.
A 12 megapixel phone photo gives about 168 DPI at 18 × 24: a good wall print. AI art at 1024 × 1365 needs about 2.6× upscaling to reach 150 DPI.
18×24" at a glance
| Size | 457.2 × 609.6 mm · 45.72 × 60.96 cm · 18 × 24 in |
|---|---|
| Shape (aspect ratio) | 3 : 4 |
| Common uses | Movie posters, art exhibition prints, commercial retail displays. |
Pixels needed for 18×24"
| Resolution | Pixels (width × height) | Megapixels | Best for |
|---|---|---|---|
| 300 DPI | 5400 × 7200 | 38.9 MP | Close up (photos, cards, documents) |
| 240 DPI | 4320 × 5760 | 24.9 MP | Framed and wall prints |
| 150 DPI | 2700 × 3600 | 9.7 MP | Posters viewed from a distance |
Pixel sizes are for portrait. For landscape, swap width and height.
Tips for printing at 18×24"
- Aim for 150–200 DPI rather than 300. It keeps files manageable and looks the same from normal viewing distance. See why viewing distance matters.
- One 3:4 file covers several sizes: 6 × 8, 9 × 12, 12 × 16, 15 × 20 and 18 × 24.
- Check fine text separately. Small lettering on a poster is read up close, so keep it as vector text in a PDF if possible.
18×24" questions
How many pixels is an 18 × 24 poster?
5400 × 7200 pixels at 300 DPI, 3600 × 4800 at 200 DPI, and 2700 × 3600 at 150 DPI.
Is 150 DPI enough for an 18 × 24 poster?
Yes, for viewing from about a metre or more. Up close it will look slightly soft, so use 200 DPI or more for art that people will inspect closely.
Can I print a phone photo at 18 × 24?
Yes. A 12 megapixel phone photo is the same 3:4 shape and gives about 168 DPI, which looks good on a wall.
Simple Process
How PrintCheck Works
Three quick steps to ensure your physical prints never come out blurry or pixelated.
Input Target Dimensions
Specify the physical width and height in millimeters (mm) along with your required DPI (300 DPI fine art or custom DPI).
Upload Your Image
Select your image file. We read its pixel size and format, then delete it straight away. Your image is never kept.
Get 3-Tier Results
Instantly view whether your image passes, qualifies for AI upscaling, or requires a higher-resolution file.
Built For Print Shops & Designers
Everything You Need for Quality Control
Exact Pixel Formula
Automates (mm / 25.4) * DPI calculation instantly for any custom physical size.
Privacy-First Processing
Your image is only held while it is being checked, then deleted. We never keep, share or look at your images.
Smart AI Upscale Detection
Detects images that can be saved using modern AI upscaling up to 4× enlargement.
Standard Print Sizes & Pixel Resolution
Reference chart of required pixel dimensions for standard photo, poster, and paper formats.
Pixels = Inches × Target DPI
Example for 8×10" at 300 DPI: (8 × 300) = 2400 px width, (10 × 300) = 3000 px height.
Pixels = (Millimeters ÷ 25.4) × Target DPI
Example for A4 (210×297 mm) at 300 DPI: (210 ÷ 25.4 × 300) = 2480 px, (297 ÷ 25.4 × 300) = 3508 px.
| Print Format | Inches | Metric (mm) | 300 DPI (Gallery Sharp) | 150 DPI (Poster Standard) | Instant Check |
|---|---|---|---|---|---|
| A4 Paper (ISO Standard) | 8.27 × 11.69" | 210.0 × 297.0 mm | 2480 × 3508 px | 1240 × 1754 px | Check A4 |
| A3 Poster (ISO Standard) | 11.69 × 16.54" | 297.0 × 420.0 mm | 3508 × 4961 px | 1754 × 2480 px | Check A3 |
| A5 Booklet (ISO Standard) | 5.83 × 8.27" | 148.0 × 210.0 mm | 1748 × 2480 px | 874 × 1240 px | Check A5 |
| 4x6" Photo (US Photo) | 4.0 × 6.0" | 101.6 × 152.4 mm | 1200 × 1800 px | 600 × 900 px | Check 4×6" |
| 5x7" Photo (US Photo) | 5.0 × 7.0" | 127.0 × 177.8 mm | 1500 × 2100 px | 750 × 1050 px | Check 5×7" |
| 8x10" Print (US Photo & Art) | 8.0 × 10.0" | 203.2 × 254.0 mm | 2400 × 3000 px | 1200 × 1500 px | Check 8×10" |
| 11x14" Print (US Wall Art) | 11.0 × 14.0" | 279.4 × 355.6 mm | 3300 × 4200 px | 1650 × 2100 px | Check 11×14" |
| 12x18" Poster (Posters) | 12.0 × 18.0" | 304.8 × 457.2 mm | 3600 × 5400 px | 1800 × 2700 px | Check 12×18" |
| 18x24" Poster (Posters) | 18.0 × 24.0" | 457.2 × 609.6 mm | 5400 × 7200 px | 2700 × 3600 px | Check 18×24" |
| 24x36" Poster (Posters) | 24.0 × 36.0" | 609.6 × 914.4 mm | 7200 × 10800 px | 3600 × 5400 px | Check 24×36" |
Answers To Common Questions
Frequently Asked Questions
Print Guides
Learn how to get sharp prints
How to Check an Image’s Resolution on Windows, Mac, iPhone and Android
Step-by-step for every device, which number to look at, and which one to ignore.
How to Print AI Art Sharp: Sizes, Upscaling and Common Problems
How far a 1024 px image goes, the upscale factor for popular sizes, and what to fix before printing.
Print-on-Demand Image Requirements: A Guide for Gelato, Printful and Printify Sellers
Resolution, templates, transparency and colour: how to prepare designs that print well on shirts, mugs and wall art.
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