Inventory Weight

Inventory Weight is a realistic encumbrance system mod for Minecraft that applies movement penalties based on how heavy your inventory is. Every item has a weight, and carrying too much will slow you down, reduce your jump height, drain your stamina, and even attract hostile mobs.

The goal is immersive survival gameplay where inventory management matters. Pack light to stay agile, or load up on gear and accept the consequences. The mod provides rich feedback through HUD elements, sounds, particles, and status effects to keep you aware of your burden.

Key Features

Dynamic weight system - Every item has a weight based on its material (ores, ingots, tools, food, etc.).
Five-tier penalty system - Progressive penalties from Light (no effect) to Crippled (barely mobile).
Movement penalties - Affects walking speed, sprint speed, jump height, swimming, and climbing.
Combat impact - Attack speed slows and fall damage increases when overloaded.
Stamina system - Optional stamina bar that drains faster when heavily encumbered.
Elytra penalties - Heavier loads cause faster descent during gliding.
Mob detection - Heavy footsteps increase hostile mob detection range.
Dimension modifiers - Weight feels different in the Nether (heavier) and End (lighter).
Transport exceptions - Horses, minecarts, and boats reduce or eliminate penalties.
Rich feedback - Tier change sounds, particles, action bar messages, and status effects.
Advancement system - Unlock achievements for weight-related accomplishments.
Fully configurable - All weights, thresholds, and behaviors can be customized via JSON.

How It Works

Weight Calculation

Every 10 ticks (0.5 seconds), the mod calculates your total inventory weight:

Source	How It's Counted
Main Inventory	Full weight of all items × stack size
Hotbar	125% weight (quick-access penalty, configurable)
Armor Slots	Only worn armor counts (not armor in inventory)
Offhand	Full weight
Shulker Boxes	Base weight + 50% of contents (configurable)
Ender Chest	Contents are weightless (dimension storage)

Weight Categories

Items are automatically categorized based on their name and properties:

Category	Weight	Example Items
Heavy	5.0	Iron ore, gold ingot, anvil, cobblestone, deepslate
Medium	2.0	Pickaxe, sword, redstone, wood planks, crafted blocks
Light	0.5	Bread, seeds, leather, wool, flowers
Near-Zero	0.1	Maps, books, potions, ender pearls, music discs

Weight Tiers

Your total weight determines your tier, which sets all penalty multipliers:

Tier	Weight Range	Description
Light	0 – 50	No penalties. Full mobility.
Medium	50 – 100	Minor slowdown. Noticeable but manageable.
Heavy	100 – 175	Significant penalties. Sprinting is sluggish.
Overloaded	175 – 250	Severe penalties. Cannot sprint.
Crippled	250+	Barely mobile. Every action is labored.

Penalty Breakdown

Penalty Type	Light	Medium	Heavy	Overloaded	Crippled
Movement Speed	100%	90%	75%	55%	40%
Sprint Speed	100%	95%	70%	Disabled	Disabled
Jump Height	100%	95%	80%	60%	45%
Swim Speed	100%	90%	70%	50%	30%
Climb Speed	100%	95%	80%	60%	40%
Mining Speed	100%	95%	85%	70%	50%
Attack Speed	100%	98%	90%	80%	65%
Fall Damage	100%	100%	+15%	+35%	+50%
Exhaustion	None	None	Low	Medium	High

Stamina System

When enabled, adds an optional stamina mechanic that drains during strenuous activities:

Activity	Stamina Effect
Sprinting	Drains stamina (faster at higher weight tiers)
Swimming	Drains stamina
Standing/Walking	Regenerates stamina (slower at higher weight tiers)
Exhausted	Cannot sprint until stamina recovers

Stamina by Tier

Tier	Drain Rate	Regen Rate
Light	1.0x	1.0x
Medium	1.3x	0.9x
Heavy	1.8x	0.7x
Overloaded	2.5x	0.4x
Crippled	3.5x	0.2x

A stamina bar appears on-screen when enabled (position configurable).

Elytra Flight

Weight significantly impacts elytra gliding performance:

Tier	Sink Rate Modifier	Effect
Light	1.0x	Normal flight
Medium	1.1x	Slightly faster descent
Heavy	1.3x	Noticeable descent increase
Overloaded	1.6x	Rapid descent
Crippled	2.0x	Difficult to maintain altitude

Heavy players will need more rockets and struggle to glide long distances.

Mob Detection System

Heavier loads make you easier to detect by hostile mobs:

Mechanic	How It Works
Detection Radius	Mobs detect you from further away based on weight tier
Footstep Volume	Louder footsteps at higher weight tiers
Stealth Impact	Sneaking is less effective when heavily loaded

Detection Radius by Tier

Tier	Detection Bonus
Light	+0% (normal)
Medium	+10%
Heavy	+25%
Overloaded	+50%
Crippled	+75%

Dimension & Environment Modifiers

Weight feels different depending on where you are:

Dimension Multipliers

Dimension	Weight Multiplier	Reason
Overworld	1.0x	Standard gravity
Nether	1.15x	Oppressive heat increases burden
End	0.85x	Lower gravity reduces effective weight

Environmental Effects

Condition	Effect
Underwater	Depth adds pressure penalty
Rain	Wet items weigh 10% more
High Altitude (Y>128)	Slight weight reduction
Deep Caves (Y<0)	Slight weight increase

Transport Exceptions

Certain vehicles reduce or eliminate weight penalties:

Transport	Effect
Horses, Donkeys, Llamas	Full immunity to weight penalties
Minecarts	Full immunity to weight penalties
Boats	50% penalty reduction (configurable)
Pigs (with saddle)	No exception (you're still carrying it)

This encourages using mounts for long-distance travel when heavily loaded.

Feedback System

The mod provides extensive feedback to keep you informed:

Visual Feedback

Element	Description
HUD Display	Shows current weight and tier on-screen
Stamina Bar	Visual bar showing remaining stamina
Item Tooltips	Weight value shown on every item
Tier Change Particles	Visual effect when entering a new tier
Action Bar Messages	Contextual warnings about encumbrance

Audio Feedback

Sound	Trigger
Armor Clink	Weight tier increased
Level-Up Chime	Weight tier decreased
Heavy Footsteps	Walking at high weight tiers (louder steps)

Status Effects (Optional)

Effect	Condition
Slowness I	Applied at Overloaded tier
Mining Fatigue I	Applied at Crippled tier
Speed I	Optional boost at Light tier (reward for traveling light)

Advancements

Unlock achievements for weight-related accomplishments:

Advancement	Requirement
Light Traveler	Travel 10,000 blocks while at Light tier
Pack Mule	Reach the Heavy weight tier
Beast of Burden	Reach the Overloaded tier
Immovable Object	Reach the Crippled tier
Marathon Runner	Travel 5,000 blocks while Heavy or above
Deep Diver	Descend 20 blocks in water while heavy
Mountain Climber	Climb 100 blocks on ladders while heavy

Statistics Tracking

The mod tracks your weight-related statistics:

Statistic	Description
Peak Weight	Highest weight ever reached
Average Weight	Running average over your play session
Distance (Light)	Total blocks traveled at Light tier
Distance (Heavy)	Total blocks traveled at Heavy+ tiers
Tier Changes	Number of times you've changed tiers
Exhaustion Count	Times stamina was fully depleted

View your stats with /weight stats.

Commands

Command	Permission	Description
`/weight check`	All	View current weight, tier, and stamina
`/weight thresholds`	All	Display tier threshold values
`/weight stats`	All	View your weight statistics
`/weight reload`	OP	Reload config from file
`/weight toggle`	OP	Enable/disable weight system globally
`/weight hardcore`	OP	Toggle hardcore mode (1.5x penalties)
`/weight stamina`	OP	Toggle stamina system
`/weight dimension`	OP	Toggle dimension modifiers
`/weight effects`	OP	Toggle status effects
`/weight set <item> <weight>`	OP	Set custom weight for any item

Configuration

Config file location: .minecraft/config/inventoryweight.json

The config file is created automatically on first launch. All options:

{
  "enabled": true,
  "showHud": true,
  "hotbarWeightMultiplier": 1.25,
  "hardcoreMode": false,
  "hardcoreMultiplier": 1.5,
  "lightTierThreshold": 0.0,
  "mediumTierThreshold": 50.0,
  "heavyTierThreshold": 100.0,
  "overloadedTierThreshold": 175.0,
  "crippledTierThreshold": 250.0,
  "categoryWeightHeavy": 5.0,
  "categoryWeightMedium": 2.0,
  "categoryWeightLight": 0.5,
  "categoryWeightNearZero": 0.1,
  "horseIgnoresWeight": true,
  "minecartIgnoresWeight": true,
  "boatPartiallyIgnoresWeight": true,
  "boatWeightReduction": 0.5,
  "showWeightInTooltip": true,
  "weightAffectsSwimming": true,
  "weightAffectsClimbing": true,
  "weightAffectsFallDamage": true,
  "weightCausesExhaustion": true,
  "weightAffectsMining": true,
  "weightAffectsAttackSpeed": true,
  "weightAffectsElytra": true,
  "shulkerBoxAddsContentWeight": true,
  "shulkerBoxBaseWeight": 3.0,
  "shulkerContentWeightMultiplier": 0.5,
  "playTierChangeSounds": true,
  "showTierChangeParticles": true,
  "staminaEnabled": false,
  "maxStamina": 100.0,
  "baseStaminaDrain": 1.0,
  "baseStaminaRegen": 0.5,
  "showStaminaBar": true,
  "staminaBarX": 10,
  "staminaBarY": 60,
  "dimensionModifiersEnabled": true,
  "netherWeightMultiplier": 1.15,
  "endWeightMultiplier": 0.85,
  "overworldWeightMultiplier": 1.0,
  "waterDepthPenaltyEnabled": true,
  "rainWeightMultiplier": 1.1,
  "altitudeModifierEnabled": true,
  "mobDetectionEnabled": true,
  "baseDetectionRadius": 16.0,
  "footstepVolumeEnabled": true,
  "weightAppliesStatusEffects": false,
  "slownessAtOverloaded": true,
  "miningFatigueAtCrippled": true,
  "speedBoostWhenLight": false,
  "customItemWeights": {}
}

Config Options Explained

Option	Default	Description
`enabled`	`true`	Master toggle for the entire mod
`showHud`	`true`	Display weight/tier HUD on screen
`hotbarWeightMultiplier`	`1.25`	Multiplier for items in hotbar slots
`hardcoreMode`	`false`	Enable harsher penalties
`hardcoreMultiplier`	`1.5`	Penalty multiplier in hardcore mode
`*TierThreshold`	varies	Weight thresholds for each tier
`categoryWeight*`	varies	Base weight for each item category
`horseIgnoresWeight`	`true`	No penalties while riding horses
`minecartIgnoresWeight`	`true`	No penalties while in minecarts
`boatPartiallyIgnoresWeight`	`true`	Reduced penalties in boats
`boatWeightReduction`	`0.5`	Penalty reduction while in boats
`showWeightInTooltip`	`true`	Show weight in item tooltips
`weightAffects*`	`true`	Toggle individual penalty types
`shulkerBoxAddsContentWeight`	`true`	Shulker contents add to weight
`shulkerBoxBaseWeight`	`3.0`	Base weight of empty shulker box
`shulkerContentWeightMultiplier`	`0.5`	Multiplier for shulker contents
`playTierChangeSounds`	`true`	Sound effects on tier change
`showTierChangeParticles`	`true`	Particle effects on tier change
`staminaEnabled`	`false`	Enable stamina system
`maxStamina`	`100.0`	Maximum stamina value
`baseStaminaDrain`	`1.0`	Base stamina drain rate
`baseStaminaRegen`	`0.5`	Base stamina regeneration rate
`showStaminaBar`	`true`	Display stamina bar on HUD
`staminaBarX/Y`	`10/60`	Stamina bar screen position
`dimensionModifiersEnabled`	`true`	Enable dimension weight modifiers
`*WeightMultiplier`	varies	Weight multiplier per dimension
`waterDepthPenaltyEnabled`	`true`	Deeper water increases penalty
`rainWeightMultiplier`	`1.1`	Weight multiplier when raining
`altitudeModifierEnabled`	`true`	Altitude affects weight
`mobDetectionEnabled`	`true`	Enable mob detection system
`baseDetectionRadius`	`16.0`	Base mob detection range
`footstepVolumeEnabled`	`true`	Weight affects footstep volume
`weightAppliesStatusEffects`	`false`	Apply status effects based on tier
`slownessAtOverloaded`	`true`	Slowness at Overloaded tier
`miningFatigueAtCrippled`	`true`	Mining Fatigue at Crippled tier
`speedBoostWhenLight`	`false`	Speed boost at Light tier

Custom Item Weights

Override any item's weight with custom values in the config:

{
  "customItemWeights": {
    "minecraft:anvil": 15.0,
    "minecraft:netherite_block": 20.0,
    "minecraft:feather": 0.05,
    "modid:custom_item": 3.0
  }
}

Multiplayer Compatibility

This mod works on both client and server. For full functionality:

Setup	Result
Client + Server	Full experience with all features
Client Only	Partial (HUD works, but penalties may not sync)
Server Only	Penalties work, but no client-side HUD/tooltips

For the best experience, install on both client and server.

Multiplayer Features

Weight calculations are done server-side for security
Movement modifiers use vanilla attribute system
Per-player weight data stored in concurrent hash maps
State synchronized properly between client and server

Installation

Install Fabric Loader (0.15.6 or newer) for Minecraft 1.20.1.
Install Fabric API (0.92.0+1.20.1 or newer).
Download the mod JAR file.
Place the JAR into your .minecraft/mods folder.
Launch Minecraft with the Fabric profile.

Building from Source

Clone the repository and run the Gradle build:

git clone https://github.com/AaravVishal1/Inventory-Weight
cd Inventory-Weight
./gradlew build

The compiled JAR will be in build/libs/.

For development, you can run the client directly:

./gradlew runClient

Requirements

Dependency	Version
Minecraft	1.20.1
Fabric Loader	0.15.6+
Fabric API	0.92.0+1.20.1
Java	17+

Troubleshooting

Movement speed isn't affected

Check that the mod is enabled (/weight toggle).
Verify you're not in Creative or Spectator mode.
Make sure you're not riding a horse/minecart (transport exception).
Check your weight with /weight check to see your current tier.

Weight seems too punishing

Lower the tier thresholds in the config to require more weight.
Reduce category weights for item types you carry often.
Disable hardcore mode if enabled.
Disable individual penalties (swimming, climbing, etc.) as needed.

Stamina drains too fast

Reduce baseStaminaDrain in the config.
Increase maxStamina for a larger pool.
Carry lighter loads more often.

HUD/tooltips not showing

Enable showHud and showWeightInTooltip in config.
Make sure you have the client-side mod installed.
Try reloading with /weight reload.

Items have wrong weights

Use /weight set <item> <weight> to assign custom weights.
Edit customItemWeights in the config file directly.
Category assignment is based on item name keywords.

Mod conflicts with other mods

The mod uses standard Fabric events and mixins.
If another mod modifies player movement, there may be conflicts.
Report issues with specific mod combinations.

Technical Details

Performance

Weight recalculated every 10 ticks (0.5 seconds)
Immediate recalculation on inventory change events
Minimal performance impact during normal gameplay

Mixins Used

Mixin	Purpose
`PlayerEntityMixin`	Movement speed modification
`LivingEntityMixin`	Jump velocity and knockback
`ServerPlayerEntityMixin`	Server-side sprint prevention
`ClientPlayerEntityMixin`	Client-side sprint prevention
`FallDamageMixin`	Fall damage scaling
`SwimmingMixin`	Swimming speed reduction
`ClimbingMixin`	Ladder/vine climbing speed
`HungerMixin`	Weight-based exhaustion
`BlockBreakMixin`	Mining speed reduction
`ElytraMixin`	Elytra flight penalties
`FootstepMixin`	Footstep volume modification

Compatibility

Compatible with most Fabric mods
Uses standard Fabric events and mixins
Does not modify vanilla items or add new content
Works with modded items (auto-categorized by name)

License

This project is licensed under the MIT License.

Inventory Weights