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This guide will help you convert your first Minecraft world between Java and Bedrock editions using Chunker.

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Prerequisites

Before you begin, ensure you have:
  • Java 17 or higher installed
  • A Minecraft world to convert (backed up!)
  • At least 4GB of available RAM
Always backup your worlds before conversion to prevent any data loss.

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Choose your method

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Desktop application quickstart

1

Download and install

Download the latest Chunker desktop application from the GitHub releases page.
# Download Chunker.exe
# Double-click to run
2

Select your world

  1. Click Select World in the application
  2. Navigate to your Minecraft world folder:
    • Java: .minecraft/saves/WorldName
    • Bedrock: Check your game’s storage location
  3. Select the world folder (or drag and drop)
3

Choose output format

  1. Click Export As
  2. Select the target edition and version
    • For Java → Bedrock: Select a Bedrock version (e.g., 1.20.80)
    • For Bedrock → Java: Select a Java version (e.g., 1.20.5)
  3. Click Continue
4

Start conversion

  1. Review advanced settings if needed (optional)
  2. Click Start Conversion
  3. Wait for the progress bar to complete
  4. Choose where to save your converted world

Learn more about the desktop app

Explore advanced features, settings, and troubleshooting

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Available formats

To see all available output formats, run: 
java -jar chunker-cli.jar -f ?
This will list all supported versions in the format EDITION_VERSION, such as:
  • JAVA_1_20_5
  • BEDROCK_1_20_80
  • JAVA_1_21_0
Java Edition
  • JAVA_1_20_6 - Latest 1.20.x
  • JAVA_1_21_0 - Minecraft 1.21
  • JAVA_1_19_4 - Legacy 1.19
  • JAVA_1_18_2 - Legacy 1.18
Bedrock Edition
  • BEDROCK_1_20_80 - Current stable
  • BEDROCK_1_21_0 - Minecraft 1.21
  • BEDROCK_1_19_80 - Legacy 1.19

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Common conversions

Java → Bedrock

Convert Java worlds to play on Bedrock platforms (mobile, console, Windows 10)
-f BEDROCK_1_20_80

Bedrock → Java

Convert Bedrock worlds to play on Java Edition
-f JAVA_1_20_5

Version upgrade

Upgrade old worlds to newer Minecraft versions
-f JAVA_1_21_0

Version downgrade

Downgrade worlds to older versions (use with caution)
-f JAVA_1_18_2

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Troubleshooting

Increase Java heap size when running Chunker:
# Desktop app
Chunker.exe -Xmx8G

# CLI
java -Xmx8G -jar chunker-cli.jar -i "world" -f BEDROCK_1_20_80 -o "output"
Make sure you’re selecting the world folder (not a region file or level.dat):
  • Java: The folder containing level.dat and region/ directory
  • Bedrock: The folder containing level.dat and db/ directory
Large worlds can take significant time. Consider:
  • Using pruning to convert only specific regions
  • Increasing available memory
  • Running on a machine with better performance
  • Using an SSD instead of HDD
See pruning documentation for region selection.
Some blocks and items don’t have direct equivalents between editions. Chunker uses best-effort mappings, but some content may:
  • Convert to similar blocks
  • Convert to placeholder blocks
  • Be removed if no mapping exists
See supported versions for edition differences.

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Next steps

Advanced configuration

Customize conversions with block mappings, pruning, and settings

CLI reference

Learn all CLI parameters and advanced usage

Supported versions

View all supported Minecraft versions

API integration

Integrate Chunker into your Java applications

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