Resolution vs. Pixels vs. DPI: Clearing Up the Confusion

Published 2026-09-29

Resolution, pixels and DPI get used almost interchangeably when talking about images. All three relate to how sharp an image looks, but they measure different things, and which one matters depends on where the image is going.

Pixels: the dots that make up the image

A pixel is the single smallest colored dot that makes up a photo. "1080 × 1080px" means 1080 dots across and 1080 dots down. More pixels allow finer detail, at the cost of a larger file.

Resolution: how densely those pixels are packed

Resolution is often used to mean the pixel dimensions themselves (like 1920×1080 for FHD), but strictly it describes how tightly pixels are packed into a given area. That's why the same 1080px photo looks sparse filling a huge screen but crisp on a small one.

DPI: only matters for print

DPI (dots per inch) describes how many dots are printed within one inch (2.54cm) of paper. It has no direct effect on how sharp an image looks on a screen, since a monitor or phone already has its own fixed pixel density. DPI is something to think about only when printing on paper.

Printing a full A4 sheet (21×29.7cm) at 300 DPI needs roughly 2480 × 3508px. Printing a 1080px photo meant for the web at that size only stays sharp at about the size of your palm.

Situations that commonly cause confusion

• A request to "increase the resolution" usually means "increase the pixel count." But stretching an already-small photo larger adds pixels without adding real detail — it just looks blurry.
• Asking for a web image at "300 DPI" is effectively meaningless. Only the pixel dimensions matter on the web.
• When a print shop asks for a "high-resolution file," what matters is whether the pixel count matches the actual print size, not the DPI number by itself.

Checking and adjusting this in prezll

prezll's Resize tool lets you type exact pixel dimensions or scale by percentage. For screens, match the pixel size the target platform recommends (Instagram's 1080 × 1350px, for example). For print, divide your target size in cm by 2.54 and multiply by 300 to get the pixel dimensions you need, then enter those.