DPI vs PPI: What’s the Difference When Printing?

If you have ever been told to “send the file at 300 DPI”, you have met one of the most confusing terms in printing. DPI and PPI are used as if they mean the same thing, but they describe two different things. Once you see the difference, it becomes much easier to know whether an image will print well.

What is PPI?

A digital image is a grid of pixels, for example 2400 pixels wide by 3000 pixels tall. On its own, that grid has no physical size. PPI describes how tightly those pixels are packed when the image is printed at a particular size.

Print that 2400 × 3000 pixel image at 8 × 10 inches and you get 300 pixels in every inch: 300 PPI. Print the same file at 16 × 20 inches and each pixel has to cover twice the width and twice the height, so you get 150 PPI. The file hasn’t changed, only the size you print it at.

What is DPI?

DPI is the number of tiny ink dots a printer places in each inch. Inkjet printers can’t print a pixel’s exact colour as one solid dot, so they build it from many smaller dots of cyan, magenta, yellow and black. That is why home printers advertise figures like 1200 or 4800 DPI. That number describes the printer’s hardware, and you don’t set it in your image file.

Why everyone says DPI anyway

The printing industry used “DPI” for decades before digital photos were common, and the habit stuck. Photoshop, print shops, print-on-demand sites and Etsy sellers all say “300 DPI” when they mean 300 PPI. That’s fine, as long as you know that what they are really asking is: does this image have enough pixels for this print size?

The “change it to 300 DPI” myth

Image files store a resolution number in their settings, often 72 or 300. Changing that number from 72 to 300 does not add a single pixel. A 1200 × 1800 pixel photo is still 1200 × 1800 pixels. You have only changed the size it would print at by default, from 16.7 × 25 inches down to 4 × 6 inches.

If you change the number with “resample” switched on in an editor, the software stretches the image and fills the gaps by blending neighbouring pixels. That gives you a bigger file but not more detail: the result usually looks soft or blurry when printed. (AI upscaling is different, see our guide to AI upscaling for print.)

The “72 DPI for web” rule is a leftover from early Apple screens. Screens show images pixel for pixel, so the number has no effect online.

What to check instead

Ignore the DPI label and look at the pixel dimensions. Then use this formula to see what you need:

For example:

There’s a bigger chart, plus advice on when less than 300 is fine, in How many pixels do you need to print?

Is 300 always needed?

No. 300 PPI is the safe standard for anything seen up close: photos, cards, flyers and books. Larger prints are viewed from further away, so they can use fewer pixels per inch without looking soft:

• 300 PPI: photos, cards, flyers, anything held in the hand.
• 200–240 PPI: framed prints and wall art viewed from a metre or so. Many photographers print at 240.
• 150 PPI: large posters and canvases viewed from across a room.
• Under 100 PPI: banners and signs viewed from several metres away.

In short

• PPI is how densely your image’s pixels are packed on paper. DPI is how many ink dots the printer uses.
• “300 DPI” from a print shop means 300 pixels per inch at the final size.
• Changing the DPI number in a file doesn’t improve quality. Only more pixels do.
• Check the pixel width and height against the size you want to print.