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This article or section documents the current version of Scratch (version 3.0). For this article in Scratch 2.0, see Project Compression (2.0). For this article in Scratch 1.4, see Project Compression (1.4).

In Scratch 3.0, the total size of a project is unlimited.[1] However, projects with large file sizes will take a very long time to load, and there are other restrictions: each costume and sound has a limit of 10 MB[2] and the project.json file, which contains the project's code, has a limit of 5 MB.[3] If a project reaches one of these two limits, there are several ways to reduce the size.

Sprites and Scripts

A project may contain unneeded sprites and scripts, which can take up lots of space. This can be reduced by deleting the unneeded sprites or scripts.

Duplicate sprites can be deleted. Stamping or cloning can be used instead.

There may be big actions that are repeated multiple times, which can take up lots of script space. This can be fixed by creating a custom block or using broadcasts.

Backdrops and Costumes

There may be backdrops or costumes that are not being used. Deleting useless backdrops and costumes will free up space.

Bitmap images can be compressed. If they are from a local computer, they can be compressed externally using a tool like TinyPNG and uploaded.

If a bitmap costume can be shown as a vector image, consider using a vector costume as vector images tend to take up less space.[citation needed]

If this is not possible, the image can be scaled down and back up, but that may cause unwanted pixelation.

Vector images can be further reduced in size by removing (and possibly replacing) excessive details such as windows on a building or fur on a hairy monster.


Unused sound files can be deleted because they take up a lot of space. Common sounds to remove are the other sounds included by default in all sprites.

If a project contains sounds are from one's hard drive, then they can be replaced with a compressed version. One way to compress sounds is to convert them to an MP3 file using this site or anything similar.

See Also


  1. Flowermanvista. (8/8/2019). "It's worth noting that these are the only size limits - there is no limit on overall project size." topic:366461
  2. Flowermanvista. (8/8/2019). "No asset can exceed 10 MB." topic:366461
  3. Flowermanvista. (8/8/2019). "The project.json file cannot exceed 5 MB." topic:366461
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