“Save it at 300 DPI.” “Export at 72 DPI for web.” You’ve seen the instructions, maybe followed them, and possibly wondered what they actually do. The short version: one of those pieces of advice is essential and the other is a myth. Here’s what resolution really means, for print and for screens.
Short answer: PPI describes pixels in an image or display; DPI describes ink dots from a printer. For anything shown on a screen, only pixel dimensions matter — the DPI number does nothing. For printing, aim for 300 DPI at the final size.
Two words for two different things
- PPI — pixels per inch. A property of a digital image or a display: how densely pixels are packed. Your phone screen might be ~460 PPI; a photo might be tagged 300 PPI.
- DPI — dots per inch. A property of a printer: how many tiny ink dots it sprays per inch of paper.
In everyday talk people swap the terms freely, and usually it doesn’t hurt. But the distinction explains the confusion: pixels are the image; dots are the ink. One lives in the file, the other happens on paper.
The screen myth: DPI does nothing online
Here’s the fact that clears up most of the confusion. An image file stores a DPI/PPI number, but screens ignore it completely. A 1000×1000-pixel image is 1000×1000 pixels whether the file says 72, 96, or 300 — the display just draws the pixels.
So “save it at 72 DPI for the web” changes nothing about how the image looks or how big the file is in any meaningful way. The advice is a leftover from old print workflows. What actually controls how an image appears on screen is its pixel dimensions — and, for file size, its compression.
This is why the profile-picture rules are all in pixels, never DPI — see profile and cover photo sizes. To make an image the right size for a screen, you change its pixel dimensions with the Image Resizer; the DPI tag is irrelevant.
Where DPI genuinely matters: printing
DPI earns its keep on paper. Here, it’s really a ratio: your image’s pixels spread across the physical print size.
pixels ÷ print inches = effective DPI
A 3000×2400 pixel photo printed at 10×8 inches is 300 DPI — crisp. Blow the same file up to 20×16 inches and it’s 150 DPI — softer. The pixels didn’t change; you spread them thinner.
| Print job | Target DPI |
|---|---|
| Photo prints, business cards, text | 300 |
| Everyday documents | 200–300 |
| Posters (viewed from a step back) | 150 |
| Billboards (viewed from far) | 25–50 |
The rule that ties it together: DPI is meaningless without a size. “300 DPI” only means something once you say at what dimensions.
How much resolution do you actually need?
Work backwards from the output:
- Screen? Ignore DPI. Match the pixel dimensions to where it’ll appear and resize with the Image Resizer.
- Print? Multiply your print size by 300. A 4×6 photo wants ~1200×1800 pixels; an 8×10 wants ~2400×3000.
Starting from a big enough original is what matters — you can always scale down cleanly, but scaling up invents detail that isn’t there and looks mushy.
Don’t confuse resolution with file size
One last mix-up: making an image “smaller” can mean two different things. Fewer pixels (lower resolution) is a job for the Image Resizer; a smaller file at the same pixels is compression, a job for the Image Compressor — covered in how to reduce image file size. DPI is involved in neither for screen use. Keep those three ideas separate — pixels, compression, print DPI — and resolution stops being mysterious.