So, I've just created an atlas A and put a number of Sprites into it. Both the atlas and the sprites are located in resources/. Then i have an atlas B and put a set of other Sprites into it. Here both the atlas and the sprites are NOT in resources/. Now when I check out the Last Build Report I can see the size of the various files in the build: Now for atlas B, the size of the build-assets are as expected for the size of the textures used. And the build-assets of the sprites used for atlas B only have small filesizes (usually sub 1kb) which indicates that there's only meta information pointing to the Atlas is included, but no actual texture information. Which feels correct since all the texture information is in the atlas B build-asset. However when I look at atlas A things are different: The atlas build-assets have the expected size. However when I look at the build-assets of the sprites used for Atlas A things are different. Here the filesizes of the build-assets are as big as the original sprites, which indicates that the entire texture information is included. This makes me wonder if the atlas is even used in that context. Does anyone have any insight? Edit: Did some further experiments. 1. Does it use the Resources/ SpriteAtlas? Test setup: New project. Added a single large sprite, made it create a mip-map (blur) and put it on a small ui image. Then I created an atlas for that single sprite, and disabled mipmapping there. Then I put both atlas and sprite in the resources/ folder and created a test build. Results: Image was crisp - i.e. used the SpriteAtlas. So that's good. Update: Tried loading the sprite not by dragging it into the slot but by loading it via Resources.Load. Same results - SpriteAtlas was used. 2. Does the build contain the Resources/ Sprite tex information? Test Setup: As above. Built once with the sprite in the resources/ folder, once with it outside, and once without an atlas. Results: Build with atlas + sprite outside resources folder: base size Build with atlas + sprite in resources folder: base size + sprite size Build without atlas: base size - atlas size. Less good, that means Unity actually adds the sprite's texture information to the build.