DPI Checker and 300 DPI Converter

How to check the DPI of an image

1. Drop a PNG, JPG or WebP into the checker. Your browser reads it; nothing is uploaded.
2. Read the DPI stored in the file and where it was found. If no DPI is stored, the checker says so instead of guessing one.
3. Read the print size: what the file gives at its own DPI, and at 300 DPI, in inches and centimetres.
4. If you need the file to say 300 DPI, download the copy in step 2. The pixels stay the same.

Without a tool, Windows shows it under Properties, then Details, as Horizontal resolution. Photoshop shows it in Image Size, and Preview on a Mac in Tools, then Show Inspector. When the file stores no DPI, those programs show a default of their own, which is why the same file can read 72 in one place and 96 in another.

DPI is a label, pixels make the print

An image file is a grid of pixels. The DPI stored with it is one extra number that tells software how many of those pixels to put in each inch of paper or fabric. Divide the pixels by the DPI and you get the print size.

A 4500 × 5400 pixel file prints 15 × 18 inches at 300 DPI. Labelled 72 DPI, it is the same 4500 × 5400 pixels; software just suggests a much larger print, 62.5 × 75 inches. Size it to 15 × 18 inches and every inch still gets 300 pixels, whatever the label said.

The opposite case is the one that hurts. A 1500 × 1800 pixel file labelled 300 DPI is sharp at 5 × 6 inches. Stretched across 15 × 18 inches it has 100 pixels in each inch, and it prints soft, even though the file still says 300.

How to change the DPI to 300 without losing quality

Changing only the label loses nothing, because nothing in the picture changes. That is what the converter above does: it rewrites the pHYs chunk of a PNG or the JFIF header of a JPG, plus any EXIF, Photoshop or XMP copy of the same number, so they all say 300. The image data is copied byte for byte. It is the same as Photoshop's Image Size with Resample turned off.

If the print size at 300 DPI comes out smaller than you need, the file needs more pixels, and a label cannot supply them. Export the design again at a larger size, go back to the original artwork, or redraw it as a vector, which prints sharp at any size. Enlarging the pixels in a resizer makes a bigger file, but the extra pixels are filled in from their neighbours, and fine lines and small text show it first.

Pixel sizes print-on-demand sites ask for

Marketplaces publish their upload sizes in pixels, because the pixels are what gets printed. These come from each platform's own help or template pages, checked in September 2026. Drop your file above and the checker compares it with every row. If a template also names a DPI, set the label to match with the converter; it changes no pixels.

To make the exact canvas, the image resizer sizes a design to any of these in one click. For DTF transfers, Transfer Superstars and t-shirt.ca ask for 300 DPI at the printed size, so a 10 inch transfer needs 3,000 pixels across; the DTF size chart lists the transfer widths by shirt size. To go from inches to pixels for any other product, use the print size calculator. Etsy listing photos are a screen job, not a print one: what counts there is the pixel size, which the Etsy image size checker lists.

A sharp file is the last step

Getting the pixels right keeps a print from looking cheap. It does not decide whether anyone orders it. That depends on the design and on how crowded its niche already is. Trendlytic, the research tool we build, reads TeePublic, Amazon Merch, Redbubble and Etsy in one search, shows the designs selling in a niche and how many sellers compete there, and marks the new designs already selling as Rising. Plans start at $19.99 a month, after a 3-day trial that takes a card.