Packet Play Client Chunk Data

1.16.2

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x22 0x20	Play	Client	Chunk X	Int	Chunk coordinate (block coordinate divided by 16, rounded down)
			Chunk Z	Int	Chunk coordinate (block coordinate divided by 16, rounded down)
			Full chunk	Boolean	See Chunk Format
			Primary Bit Mask	VarInt	Bitmask with bits set to 1 for every 16×16×16 chunk section whose data is included in Data. The least significant bit represents the chunk section at the bottom of the chunk column (from y=0 to y=15).
			Heightmaps	NBT	Compound containing one long array named MOTION_BLOCKING, which is a heightmap for the highest solid block at each position in the chunk (as a compacted long array with 256 entries at 9 bits per entry totaling 36 longs). The Notchian server also adds a WORLD_SURFACE long array, the purpose of which is unknown, but it's not required for the chunk to be accepted.
			Biomes length	Optional VarInt	Size of the following array. Not present if full chunk is false.
			Biomes	Optional array of Integer VarInt	1024 biome IDs, ordered by x then z then y, in 4×4×4 blocks. Possibly something else. Not present if full chunk is false.
			Size	VarInt	Size of Data in bytes
			Data	Byte array	See data structure in Chunk Format
			Number of block entities	VarInt	Number of elements in the following array
			Block entities	Array of NBT Tag	All block entities in the chunk. Use the x, y, and z tags in the NBT to determine their positions.





1.16

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x22 0x21	Play	Client	Chunk X	Int	Chunk coordinate (block coordinate divided by 16, rounded down)
			Chunk Z	Int	Chunk coordinate (block coordinate divided by 16, rounded down)
			Full chunk	Boolean	See Chunk Format
			Ignore old data	Boolean	If false, the client will recalculate lighting based on the old/new chunk data
			Primary Bit Mask	VarInt	Bitmask with bits set to 1 for every 16×16×16 chunk section whose data is included in Data. The least significant bit represents the chunk section at the bottom of the chunk column (from y=0 to y=15).
			Heightmaps	NBT	Compound containing one long array named MOTION_BLOCKING, which is a heightmap for the highest solid block at each position in the chunk (as a compacted long array with 256 entries at 9 bits per entry totaling 36 longs). The Notchian server also adds a WORLD_SURFACE long array, the purpose of which is unknown, but it's not required for the chunk to be accepted.
			Biomes	Optional array of Integer	1024 biome IDs, ordered by x then z then y, in 4×4×4 blocks. Not present if full chunk is false.
			Size	VarInt	Size of Data in bytes
			Data	Byte array	See data structure in Chunk Format
			Number of block entities	VarInt	Number of elements in the following array
			Block entities	Array of NBT Tag	All block entities in the chunk. Use the x, y, and z tags in the NBT to determine their positions.





1.15.2

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x22	Play	Client	Chunk X	Int	Chunk coordinate (block coordinate divided by 16, rounded down)
			Chunk Z	Int	Chunk coordinate (block coordinate divided by 16, rounded down)
			Full chunk	Boolean	See Chunk Format
			Primary Bit Mask	VarInt	Bitmask with bits set to 1 for every 16×16×16 chunk section whose data is included in Data. The least significant bit represents the chunk section at the bottom of the chunk column (from y=0 to y=15).
			Heightmaps	NBT	Compound containing one long array named MOTION_BLOCKING, which is a heightmap for the highest solid block at each position in the chunk (as a compacted long array with 256 entries at 9 bits per entry totaling 36 longs). The Notchian server also adds a WORLD_SURFACE long array, the purpose of which is unknown, but it's not required for the chunk to be accepted.
			Biomes	Optional array of Integer	1024 biome IDs, ordered by x then z then y, in 4×4×4 blocks. Not present if full chunk is false.
			Size	VarInt	Size of Data in bytes
			Data	Byte array	See data structure in Chunk Format
			Number of block entities	VarInt	Number of elements in the following array
			Block entities	Array of NBT Tag	All block entities in the chunk. Use the x, y, and z tags in the NBT to determine their positions.





1.14.4

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x21	Play	Client	Chunk X	Int	Chunk coordinate (block coordinate divided by 16, rounded down)
			Chunk Z	Int	Chunk coordinate (block coordinate divided by 16, rounded down)
			Full chunk	Boolean	See Chunk Format
			Primary Bit Mask	VarInt	Bitmask with bits set to 1 for every 16×16×16 chunk section whose data is included in Data. The least significant bit represents the chunk section at the bottom of the chunk column (from y=0 to y=15).
			Heightmaps	NBT	Compound containing one long array named MOTION_BLOCKING, which is a heightmap for the highest solid block at each position in the chunk (as a compacted long array with 256 entries at 9 bits per entry totaling 36 longs). The Notchian server also adds a WORLD_SURFACE long array, the purpose of which is unknown, but it's not required for the chunk to be accepted.
			Size	VarInt	Size of Data in bytes
			Data	Byte array	See data structure in Chunk Format
			Number of block entities	VarInt	Number of elements in the following array
			Block entities	Array of NBT Tag	All block entities in the chunk. Use the x, y, and z tags in the NBT to determine their positions.





1.13.2

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x22	Play	Client	Chunk X	Int	Chunk coordinate (block coordinate divided by 16, rounded down)
			Chunk Z	Int	Chunk coordinate (block coordinate divided by 16, rounded down)
			Full chunk	Boolean	See Chunk Format
			Primary Bit Mask	VarInt	Bitmask with bits set to 1 for every 16×16×16 chunk section whose data is included in Data. The least significant bit represents the chunk section at the bottom of the chunk column (from y=0 to y=15).
			Size	VarInt	Size of Data in bytes
			Data	Byte array	See data structure in Chunk Format
			Number of block entities	VarInt	Number of elements in the following array
			Block entities	Array of NBT Tag	All block entities in the chunk. Use the x, y, and z tags in the NBT to determine their positions.





1.13.1

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x22	Play	Client	Chunk X	Int	Chunk coordinate (block coordinate divided by 16, rounded down)
			Chunk Z	Int	Chunk coordinate (block coordinate divided by 16, rounded down)
			Ground-Up Continuous	Boolean	See Chunk Format
			Primary Bit Mask	VarInt	Bitmask with bits set to 1 for every 16×16×16 chunk section whose data is included in Data. The least significant bit represents the chunk section at the bottom of the chunk column (from y=0 to y=15).
			Size	VarInt	Size of Data in bytes
			Data	Byte array	See data structure in Chunk Format
			Number of block entities	VarInt	Number of elements in the following array
			Block entities	Array of NBT Tag	All block entities in the chunk. Use the x, y, and z tags in the NBT to determine their positions.





1.12.2

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x20	Play	Client	Chunk X	Int	Chunk coordinate (block coordinate divided by 16, rounded down)
			Chunk Z	Int	Chunk coordinate (block coordinate divided by 16, rounded down)
			Ground-Up Continuous	Boolean	See Chunk Format
			Primary Bit Mask	VarInt	Bitmask with bits set to 1 for every 16×16×16 chunk section whose data is included in Data. The least significant bit represents the chunk section at the bottom of the chunk column (from y=0 to y=15).
			Size	VarInt	Size of Data in bytes
			Data	Byte array	See data structure in Chunk Format
			Number of block entities	VarInt	Number of elements in the following array
			Block entities	Array of NBT Tag	All block entities in the chunk. Use the x, y, and z tags in the NBT to determine their positions.





1.12.1

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x20	Play	Client	Chunk X	Int	Chunk coordinate (block coordinate divided by 16, rounded down)
			Chunk Z	Int	Chunk coordinate (block coordinate divided by 16, rounded down)
			Ground-Up Continuous	Boolean	See Chunk Format
			Primary Bit Mask	VarInt	Bitmask with bits set to 1 for every 16×16×16 chunk section whose data is included in Data. The least significant bit represents the chunk section at the bottom of the chunk column (from y=0 to y=15).
			Size	VarInt	Size of Data in bytes
			Data	Byte array	See data structure in Chunk Format
			Number of block entities	VarInt	Length of the following array
			Block entities	Array of NBT Tag	All block entities in the chunk. Use the x, y, and z tags in the NBT to determine their positions.





1.12

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x20	Play	Client	Chunk X	Int	Chunk coordinate (block coordinate divided by 16, rounded down)
			Chunk Z	Int	Chunk coordinate (block coordinate divided by 16, rounded down)
			Ground-Up Continuous	Boolean	See Chunk Format
			Primary Bit Mask	VarInt	Bitmask with bits set to 1 for every 16×16×16 chunk section whose data is included in Data. The least significant bit represents the chunk section at the bottom of the chunk column (from y=0 to y=15).
			Size	VarInt	Size of Data in bytes
			Data	Byte array	See data structure in Chunk Format
			Number of block entities	VarInt	Length of the following array
			Block entities	Array of NBT Tag	All block entities in the chunk. Use the x, y, and z tags in the NBT to determine their positions.





1.11.X

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x20	Play	Client	Chunk X	Int	Block coordinate divided by 16, rounded down
			Chunk Z	Int	Block coordinate divided by 16, rounded down
			Ground-Up Continuous	Boolean	This is true if the packet represents all chunk sections in this vertical chunk column, where the Primary Bit Mask specifies exactly which chunk sections are included, and which are air.
			Primary Bit Mask	VarInt	Bitmask with bits set to 1 for every 16×16×16 chunk section whose data is included in Data. The least significant bit represents the chunk section at the bottom of the chunk column (from y=0 to y=15).
			Size	VarInt	Size of Data in bytes, plus size of Biomes in bytes if present
			Data	Array of Chunk Section	The length of the array is equal to the number of bits set in Primary Bit Mask. Chunks are sent bottom-to-top, i.e. the first chunk, if sent, extends from Y=0 to Y=15.
			Biomes	Optional Byte Array	Only if Ground-Up Continuous: biome array, byte per XZ coordinate, 256 bytes total.
			Number of block entities	VarInt	Length of the following array
			Block entities	Array of NBT Tag	All block entities in the chunk. Use the x, y, and z tags in the NBT to determine their positions.





1.11

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x20	Play	Client	Chunk X	Int	Block coordinate divided by 16, rounded down
			Chunk Z	Int	Block coordinate divided by 16, rounded down
			Ground-Up Continuous	Boolean	This is true if the packet represents all chunk sections in this vertical chunk column, where the Primary Bit Mask specifies exactly which chunk sections are included, and which are air.
			Primary Bit Mask	VarInt	Bitmask with bits set to 1 for every 16×16×16 chunk section whose data is included in Data. The least significant bit represents the chunk section at the bottom of the chunk column (from y=0 to y=15).
			Size	VarInt	Size of Data in bytes, plus size of Biomes in bytes if present
			Data	Array of Chunk Section	The length of the array is equal to the number of bits set in Primary Bit Mask. Chunks are sent bottom-to-top, i.e. the first chunk, if sent, extends from Y=0 to Y=15.
			Biomes	Optional Byte Array	Only if Ground-Up Continuous: biome array, byte per XZ coordinate, 256 bytes total.
			Number of block entities	VarInt	Length of the following array
			Block entities	Array of NBT Tag	All block entities in the chunk. Use the x, y, and z tags in the NBT to determine their positions.





1.11

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x20	Play	Client	Chunk X	Int	Block coordinate divided by 16, rounded down
			Chunk Z	Int	Block coordinate divided by 16, rounded down
			Ground-Up Continuous	Boolean	This is true if the packet represents all chunk sections in this vertical chunk column, where the Primary Bit Mask specifies exactly which chunk sections are included, and which are air.
			Primary Bit Mask	VarInt	Bitmask with bits set to 1 for every 16×16×16 chunk section whose data is included in Data. The least significant bit represents the chunk section at the bottom of the chunk column (from y=0 to y=15).
			Size	VarInt	Size of Data in bytes, plus size of Biomes in bytes if present
			Data	Array of Chunk Section	The length of the array is equal to the number of bits set in Primary Bit Mask. Chunks are sent bottom-to-top, i.e. the first chunk, if sent, extends from Y=0 to Y=15.
			Biomes	Optional Byte Array	Only if Ground-Up Continuous: biome array, byte per XZ coordinate, 256 bytes total.
			Number of block entities	VarInt	Length of the following array
			Block entities	Array of NBT Tag	All block entities in the chunk. Use the x, y, and z tags in the NBT to determine their positions.





1.10

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x20	Play	Client	Chunk X	Int	Block coordinate divided by 16, rounded down
			Chunk Z	Int	Block coordinate divided by 16, rounded down
			Ground-Up Continuous	Boolean	This is true if the packet represents all chunk sections in this vertical chunk column, where the Primary Bit Mask specifies exactly which chunk sections are included, and which are air.
			Primary Bit Mask	VarInt	Bitmask with bits set to 1 for every 16×16×16 chunk section whose data is included in Data. The least significant bit represents the chunk section at the bottom of the chunk column (from y=0 to y=15).
			Size	VarInt	Size of Data in bytes, plus size of Biomes in bytes if present
			Data	Array of Chunk Section	The length of the array is equal to the number of bits set in Primary Bit Mask. Chunks are sent bottom-to-top, i.e. the first chunk, if sent, extends from Y=0 to Y=15.
			Biomes	Optional Byte Array	Only if Ground-Up Continuous: biome array, byte per XZ coordinate, 256 bytes total.
			Number of block entities	VarInt	Length of the following array
			Block entities	Array of NBT Tag	All block entities in the chunk. Use the x, y, and z tags in the NBT to determine their positions.





1.9.3

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x20	Play	Client	Chunk X	Int	Block coordinate divided by 16, rounded down
			Chunk Z	Int	Block coordinate divided by 16, rounded down
			Ground-Up Continuous	Boolean	This is true if the packet represents all chunk sections in this vertical chunk column, where the Primary Bit Mask specifies exactly which chunk sections are included, and which are air.
			Primary Bit Mask	VarInt	Bitmask with bits set to 1 for every 16×16×16 chunk section whose data is included in Data. The least significant bit represents the chunk section at the bottom of the chunk column (from y=0 to y=15).
			Size	VarInt	Size of Data in bytes, plus size of Biomes in bytes if present
			Data	Array of Chunk Section	The length of the array is equal to the number of bits set in Primary Bit Mask. Chunks are sent bottom-to-top, i.e. the first chunk, if sent, extends from Y=0 to Y=15.
			Biomes	Optional Byte Array	Only if Ground-Up Continuous: biome array, byte per XZ coordinate, 256 bytes total.
			Number of block entities	VarInt	Length of the following array
			Block entities	Array of NBT Tag	All block entities in the chunk. Use the x, y, and z tags in the NBT to determine their positions.





1.9.2

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x20	Play	Client	Chunk X	Int	Block coordinate divided by 16, rounded down
			Chunk Z	Int	Block coordinate divided by 16, rounded down
			Ground-Up Continuous	Boolean	This is true if the packet represents all chunk sections in this vertical chunk column, where the Primary Bit Mask specifies exactly which chunk sections are included, and which are air.
			Primary Bit Mask	VarInt	Bitmask with bits set to 1 for every 16×16×16 chunk section whose data is included in Data. The least significant bit represents the chunk section at the bottom of the chunk column (from y=0 to y=15).
			Size	VarInt	Size of Data in bytes, plus size of Biomes in bytes if present
			Data	Array of Chunk Section	The length of the array is equal to the number of bits set in Primary Bit Mask. Chunks are sent bottom-to-top, i.e. the first chunk, if sent, extends from Y=0 to Y=15.
			Biomes	Optional Byte Array	Only if Ground-Up Continuous: biome array, byte per XZ coordinate, 256 bytes total.





1.9

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x20	Play	Client	Chunk X	Int	Block coordinate divided by 16, rounded down
			Chunk Z	Int	Block coordinate divided by 16, rounded down
			Ground-Up Continuous	Boolean	This is true if the packet represents all chunk sections in this vertical chunk column, where the Primary Bit Mask specifies exactly which chunk sections are included, and which are air.
			Primary Bit Mask	VarInt	Bitmask with bits set to 1 for every 16×16×16 chunk section whose data is included in Data. The least significant bit represents the chunk section at the bottom of the chunk column (from y=0 to y=15).
			Size	VarInt	Size of Data in bytes, plus size of Biomes in bytes if present
			Data	Array of Chunk Section	The length of the array is equal to the number of bits set in Primary Bit Mask. Chunks are sent bottom-to-top, i.e. the first chunk, if sent, extends from Y=0 to Y=15.
			Biomes	Optional Byte Array	Only if Ground-Up Continuous: biome array, byte per XZ coordinate, 256 bytes total.





1.8.X

Packet ID	State	Bound To	Field Name	Field Type	Notes
0x21	Play	Client	Chunk X	Int	Chunk X coordinate
			Chunk Z	Int	Chunk Z coordinate
			Ground-Up Continuous	Boolean	This is true if the packet represents all sections in this vertical column, where the Primary Bit Mask specifies exactly which sections are included, and which are air
			Primary Bit Mask	Unsigned Short	Bitmask with 1 for every 16x16x16 section whose data follows in the compressed data
			Size	VarInt	Size of Data
			Data	Chunk