FatStack adds a config file to change the default max stack size for all items.
At startup it'll generate a config file with a set of defaults, and that config file can be changed to change the default max stack size of any item.
The mod can be run purely on the server, and when items are sent to the client they spoof the minecraft:max_stack_size item component, so the clients are notified of the changes.
Quick facts
- Edition: Minecraft Java
- File type: .jar
- Minecraft versions listed: 1.21.9, 1.21.10
- How to install: Install the matching mod loader (Forge, Fabric or NeoForge) for your Minecraft version. → Download the .jar. → Put it in the .minecraft/mods folder and launch that loader profile.
- Where to get it: Opens on Modrinth — not every file is mirrored on our own servers.
Install steps are the general flow for this file type — How to install Minecraft Java mods & modpacks walks through it step by step.
Verified by MCModsHub
- Ships as fatstack-1.1+mc.1.21.10.jar — drop this file into the mods folder
- Download size: 13 KB
- Download link checked 5 Sept 2026 — working
These come from our own check of the pack file, not from the source page.