PDF DPI Checker — Image Resolution & Print Readiness
When you send a PDF to a print shop or prepare one for professional publishing, the images inside it need to be at a high enough resolution to look sharp on paper. This tool checks the DPI of images embedded in a PDF without you needing to install any software. Upload your PDF file and the tool reads the file structure directly in your browser. It finds every image object inside the document, reads the pixel dimensions stored in the PDF metadata, and calculates the effective dots per inch based on the page size. It also identifies the paper format, PDF version, image compression type, and color space for each image. The results include a per-image verdict and an overall print-readiness rating so you know at a glance whether your PDF is ready for professional printing or needs to be re-exported at higher quality. Your file is processed locally and is never uploaded to any server.
Your file is read locally in the browser. Nothing is uploaded to any server.
Frequently Asked Questions
What DPI does a PDF need to be for printing?
For professional commercial printing, embedded images in a PDF should be at least 300 DPI at the final print size. Images at 150 to 299 DPI work for standard office or inkjet printing but may look slightly soft. Images below 150 DPI will appear pixelated when printed. Press-quality files for offset or digital printing typically target 300 to 600 DPI.
What does DPI mean in a PDF?
DPI stands for dots per inch. In a PDF it refers to the pixel density of raster images embedded in the document. Higher DPI means more pixels packed into each inch of printed output, which produces sharper results. Vector elements like text, lines, and shapes are resolution-independent and always print at maximum quality regardless of the DPI setting.
How do I check the DPI of images in a PDF?
Upload your PDF to this tool and it parses the file structure in your browser, finds each embedded image object, reads its pixel dimensions from the object metadata, and calculates effective DPI based on the page size. Professional tools like Adobe Acrobat Pro have a preflight panel that reports the same information for each image in the document.
Why are images in my PDF low resolution?
Low resolution in a PDF usually comes from one of three causes. The original images were already low resolution before being placed in the document. The PDF was exported with compression settings that reduced image quality to keep the file size small. Or the file was saved for screen viewing at 72 or 96 DPI rather than print quality. Re-exporting from the source application with high-resolution image settings usually resolves this.
Does this tool work with password-protected PDFs?
No. If a PDF is encrypted or password-protected, the internal structure is scrambled and the tool cannot read the image metadata or page dimensions. You need to unlock the PDF using the password and save an unprotected copy before uploading it to this tool.
What DPI should I use when saving images for print?
For professional print (brochures, posters, business cards): 300 DPI minimum. For large-format printing viewed from a distance (banners, trade show displays): 100-150 DPI is acceptable since viewers stand further away. For newspapers: 150-200 DPI. For digital-only content: DPI does not affect quality — only pixel dimensions matter. Always check your printer's requirements before finalizing artwork.
Why does my PDF look blurry when printed?
A blurry printed PDF usually means the embedded images have too few pixels per inch (under 150 DPI at print size). Images that look fine on screen may appear blurry when printed because screens display at 72-96 DPI while printers output at 300+ DPI. Use this tool to check the actual DPI of images in your PDF before sending to print. Images originally saved at 72 DPI cannot be fixed by simply changing the DPI setting — you need higher-resolution source files.
What is the difference between DPI and PPI?
DPI (dots per inch) refers to the physical output resolution of a printer — how many ink dots it places per inch. PPI (pixels per inch) refers to the pixel density of a digital image or screen. In common usage these terms are often used interchangeably, but technically: your camera captures images in PPI, and your printer outputs in DPI. When preparing print files, the PPI of your image should match or exceed the DPI your printer needs.
How It Works
This tool reads your PDF using PDF.js (Mozilla's open-source PDF renderer). It parses the internal PDF structure to find embedded image objects and reads their pixel dimensions and declared DPI metadata. Page dimensions come from the PDF MediaBox. Effective print DPI is calculated as image pixel width divided by the image width in inches as printed. All processing is local — your file is never uploaded.
DPI Requirements by Output
Screen/web: DPI is irrelevant (pixel dimensions matter). Home inkjet: 150 DPI minimum. Professional offset print: 300 DPI required. Large-format banner (viewed from 3ft+): 100-150 DPI. Newspaper: 170-200 DPI. Fine art giclée: 360+ DPI. Billboard (viewed from 50ft+): 15-30 DPI. Always verify requirements with your print provider — specifications vary by equipment.
Why Low DPI Happens
Low-resolution images in PDFs typically come from: screenshots (72-96 DPI), images downloaded from websites, photos shared via messaging apps (compressed), or images scaled up beyond their native size in layout software. Changing the DPI number in software does not add pixels — you need higher-resolution source files. The only fix is to replace low-res images with the original high-resolution versions.
When to Use This
Use before sending a PDF to a commercial printer, when a printer flags your file as low-resolution and you need to find which images are the problem, to verify design files from a client meet print standards, or to audit a brochure or portfolio PDF before an important deadline or submission.
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