I need to send a flyer to a local print shop, and they require the PDF to be at least 300 DPI. I already looked in the file properties on my Windows laptop, but I only see the page dimensions in inches. How can I actually check the resolution of the images inside the document before I submit it?
Honestly, the PDF itself doesn’t have one DPI, only the images inside it do. Quick check I use at work: zoom in to 300 or 400 percent and see if it stays sharp or gets blocky. For a real number, take the image’s pixel width and divide by how many inches wide it prints.
I had this exact problem with our clinic leaflets last year. Windows won’t show it because a PDF only holds individual images, each with its own DPI (dots per inch). What worked for me was using PDFcap at pdfcap.com to check and optimise the images to 300 DPI before sending them off to the printer.
I learnt the hard way with my market price lists that Windows properties will not tell you the DPI. Just open the file in your web browser and zoom in to about 400 percent. If the images look fuzzy, they are nowhere near 300 DPI. Avoid using photos saved straight from social media, as they are usually low resolution and will look dreadful on paper.
Had the same thing last month before sending a sponsor flyer to print. Windows file properties won’t show it, so I just open the PDF in Preview if I’m on a Mac, or zoom to 100 percent in a browser and compare pixel size to the printed inches. Easiest check: take the image’s pixel width, divide by the inches you want it printed at, and see if that lands near 300. Learned the hard way that a flyer looking fine on screen can still print blurry.
sarcastic_sea Good point about social media photos, those are usually 72 dpi. On my old laptop 400 percent zoom always looks blocky, so I take the pixel width and divide by the printed inches instead.
@Emily.7 Fwiw, social media images aren’t always exactly 72 DPI, but they usually have too few pixels for a large print. The reliable check is pixel width divided by the intended printed width in inches, so 1800 pixels printed at 6 inches is 300 DPI.
I usually open it in Acrobat’s Print Production tools and run Output Preview or Preflight, which reports the effective resolution of each image. If you do not have Acrobat, extract or inspect the placed images with a PDF tool, then check pixel dimensions against their size on the page. For example, an image printed 4 inches wide needs about 1200 pixels wide for 300 dpi.
A PDF doesn’t have one overall DPI; each raster image’s effective resolution is its pixel width divided by its printed width in inches. In Acrobat, select an image and open Properties to check both values. Text and vector artwork are resolution-independent, but ask whether the shop means embedded raster images must reach 300 DPI at final size.
@evelyn2008 That’s the same math I use. For the scanned claim files I process, I grab the pixel width of each image and divide by its printed width in inches, then flag anything under 300. Simpler than running a full preflight when there are only a couple of images to check.