Inventory Weight

Appearance

Custom Item Weights ​

Custom item weights let modpack makers and server owners override the weight of specific items.

MT Inventory Weight now uses a data-driven datapack system for item-specific weights.

WARNING

The old custom item weight config file is no longer used.

Old versions used:

text
config/inventoryweight/inventory_weights_items.json

Some transitional builds may also have used item-specific TOML config files.

These files are no longer read by MT Inventory Weight. Move custom item weights into datapack JSON files instead.

Where Custom Item Weights Go ​

Custom item weight datapack files go here:

text
data/<namespace>/inventory_weight/items/*.json

Example:

text
data/my_weight_pack/inventory_weight/items/custom_weights.json

Simple Object Format ​

json
{
  "minecraft:diamond_sword": 350.0,
  "minecraft:gold_ingot": 100.0
}

In this example:

  • minecraft:diamond_sword weighs 350.0
  • minecraft:gold_ingot weighs 100.0

Object-with-Weight Format ​

You can also write:

json
{
  "minecraft:diamond_sword": {
    "weight": 350.0
  },
  "minecraft:gold_ingot": {
    "weight": 100.0
  }
}

Array Format ​

json
[
  {
    "item": "minecraft:diamond_sword",
    "weight": 350.0
  },
  {
    "item": "minecraft:gold_ingot",
    "weight": 100.0
  }
]

NBT-Specific Custom Weights ​

NBT-specific rules allow one item type to have different weights depending on its NBT data.

Example:

json
{
  "minecraft:bundle": {
    "weightWhenNbt": {
      "Items": {
        "value": "minecraft:glass",
        "weight": 100.0
      }
    }
  }
}

This can be used for:

  • filled containers
  • upgraded items
  • items with custom modes
  • modded items with NBT data
  • special variants of the same item

Example Datapack ​

Folder structure:

text
my_weight_pack/
├─ pack.mcmeta
└─ data/
   └─ my_weight_pack/
      └─ inventory_weight/
         └─ items/
            └─ custom_weights.json

pack.mcmeta for Minecraft 1.20.1:

json
{
  "pack": {
    "pack_format": 15,
    "description": "Custom MT Inventory Weight item weights"
  }
}

custom_weights.json:

json
{
  "minecraft:iron_ingot": 100.0,
  "minecraft:diamond": 200.0,
  "minecraft:obsidian": 1200.0
}

Loading Custom Weights ​

Datapack item weights are loaded:

  • when the server starts
  • when /reload is used

The server syncs resolved item weight data to clients so tooltips match the server.

Conflict Handling ​

If the same item is defined in multiple datapack files, MT Inventory Weight logs a warning.

The first loaded definition is kept.

WARNING

Avoid defining the same item in multiple datapacks unless you intentionally rely on datapack load order.

Custom Weights vs Default Weights ​

Custom datapack weights override the automatic default calculation.

If no custom datapack weight exists, the mod falls back to automatic calculation based on:

  • item category
  • stack size
  • durability
  • rarity
  • food value
  • block hardness
  • blast resistance
  • and other built-in rules

Custom Weights vs Add-ons ​

Add-ons can also provide item weights through the API.

Depending on provider priority, an add-on may override or run before datapack weights.

For developer integrations, see:

Migrating from Old Configs ​

Old config example:

json
{
  "minecraft:diamond_sword": 100.0,
  "minecraft:gold_ingot": 50.0
}

New datapack equivalent:

json
{
  "minecraft:diamond_sword": 100.0,
  "minecraft:gold_ingot": 50.0
}

The JSON object can look similar, but the file must now be inside a datapack path:

text
data/<namespace>/inventory_weight/items/*.json

not inside:

text
config/inventoryweight/