What is an MCR file?
The Minecraft MCR file format is a data format used by Minecraft to store terrain chunks of a Minecraft World. It is based on the NBT (Named Binary Tag) format, which was developed by the developers of the popular open-source game engine, Minecraft Forge. MCR file type was introduced in the very beginning and was later replaced by the MCA file format.
MCR File Format
The MCR file format is structured as a series of named binary tags, each of which contains a specific type of data. The top-level tag is the “Level” tag, which contains all of the data for a single game level. Within the Level tag, there are several other named tags that store different types of data, such as the “Data” tag, which stores information about the game world, and the “Entities” and “TileEntities” tags, which store data about the game objects and tile entities in the world, respectively.
What is inside MCR File Format?
In the Minecraft MCR file format, a region is a 32x32 block area of the game world. The MCR format divides the game world into regions in order to manage the data more efficiently and allow for faster loading and saving of game levels. Each region is stored in a separate file, and the MCR file format uses a system of coordinates to identify the position of each region within the game world. The coordinates of a region are determined by the block coordinates of the lower-left corner of the region. For example, a region with coordinates (-1,0) would be located one region to the left and zero regions down from the origin of the game world.
Key Characteristics of MCR Files
| Characteristic | Description |
|---|---|
| File Extension | .mcr |
| Primary Variants | Original McRegion format introduced in Minecraft Beta 1.3; later succeeded by the Anvil (MCA) format in Minecraft 1.2.1; no official version variants beyond the standard McRegion implementation |
| Format Type | Binary region file format based on the Named Binary Tag (NBT) structure; features an 8 KiB header (split into location and timestamp tables of 1024 entries each) followed by GZip or Zlib compressed chunk data stored in 4 KiB sectors |
| Primary Use | Storing region data for Minecraft Java Edition worlds from Beta 1.3 through release 1.1; each region covers a 32x32 chunk area (512x256x512 blocks) and contains block data, entities, tile entities, and lighting information |
| Main Feature | Revolutionary region-based storage that grouped chunks together, eliminating the performance issues of the earlier Alpha level format where each chunk was saved as an individual file; reduced world loading pauses by up to seven times |
| Security Profile | Safe for game use; contains no built-in checksums for data integrity verification; susceptible to corruption if manually edited with text editors; requires specialized tools (NBTExplorer, Minecraft Region Fixer) for safe viewing and modification |
| Compatibility | Native to Minecraft Java Edition versions Beta 1.3 through 1.1; automatically converted to MCA format when loaded in Minecraft 1.2.1 or later; can be opened and inspected using third-party tools like NBTExplorer, MCEdit, or Python-based region fixers |
MCR File Format Specifications
The MCR file format specifications are publicly available. The specifications for the NBT format, upon which the MCR format is based, are available on the Minecraft Forge website. Additionally, the Minecraft Wiki also has detailed information about the MCR file format, including its structure and the various data types that it supports.
Compressed Data in MCR Files
The Minecraft MCR file format supports compression. MCR file format is based on the The NBT format that allows data to be stored in a compressed form. This helps to reduce the size of MCR files and make them more efficient to transfer and store. This is an important feature of the MCR file format, as it allows players to share large Minecraft World terrain data with others.
MCR vs. MCA: Key Differences
The Anvil format (MCA) introduced several improvements over MCR:
| Feature | MCR (Old) | MCA (Anvil) |
|---|---|---|
| Build Height | 128 blocks | 256 blocks |
| Block ID Limit | 256 | 4096 (with 4-bit data layer) |
| Empty Chunks | Loaded into memory | Not loaded or saved |
| Biome Data | Calculated on the fly | Saved per X,Z column (editable) |
| Block Ordering | XZY | YZX (improves compression) |
| Chunk Packets | Less optimized | Optimized for size |
FAQ
Q1: What does MCR stand for in Minecraft?
A: MCR stands for Minecraft Region, reflecting that the format stores game world data divided into 32x32 chunk regions.
Q2: Can I open MCR files without Minecraft?
A:Yes, you can view and edit MCR files using third-party tools like NBTExplorer, but you need Minecraft to actually play the world.
Q3: What is the difference between MCR and MCA files?
A: MCA (Anvil) is the newer format that replaced MCR in Minecraft 1.2.1, offering double the build height (256 vs 128 blocks) and better storage efficiency
Q4: Is an MCR file a complete Minecraft world?
A: No, a single MCR file only stores one region of a world. A complete Minecraft world consists of many MCR files in the “region” folder.
Q5: Can I delete MCR files if my world has MCA files?
A: Yes, if your world has been converted to the newer Anvil format, the old MCR files are left behind as a compatibility measure and can be safely deleted to save space.
