Inventory

Minecraft displays the player inventory differently, according to how the window was opened. Ranges of slot indices vary in meaning between different “windows”. Minecraft indicates which window is being opened according to:

Inventory type	Description	Block ID	Entity ID
0	Chest, large chest, or minecart with chest	minecraft:chest	MinecartChest
1	Crafting table	minecraft:crafting_table
2	Furnace	minecraft:furnace
3	Dispenser	minecraft:dispenser
4	Enchantment table	minecraft:enchanting_table
5	Brewing stand	minecraft:brewing_stand
6	Villager		Villager
7	Beacon	minecraft:beacon
8	Anvil	minecraft:anvil
9	Hopper or minecart with hopper	minecraft:hopper	MinecartHopper
10	Dropper	minecraft:dropper
11	Horse, donkey, or mule		EntityHorse

The slot number is calculated starting at 0, counting up through the window's unique slots, and then counting through the players inventory. The number of unique slots in the window is in the Open Window (Play, 0x2d, clientbound) packet for all window types except the default inventory window, in which the number of unique slots is 9. This means the slot in the upper-left corner of the player's inventory is slot n where n is the number of unique slots. Slot number -999 is used for clicking outside the window.

Rectangular regions are always indexed starting with the upper-left corner and scanning across rows. If a window has a crafting region, the output slot is always slot 0 followed immediately by the input region.

Each window type is described in the following sections. All slot index ranges are inclusive and reflect the indices observed in the Minecraft protocol.

For the window properties (additional data in each window, e.g. smelting progress or enchantments), refer to the table in the Window Property packet.

Inventory

Inventory slots

This is the inventory window that the player can always open, typically by pressing E since Beta 1.4. Before, you had to press I.

Slot range	Description
0	crafting output
1–4	2×2 crafting input (1 + x + 2 * y)
5–8	armor (head, chest, legs, feet)
9–35	main inventory
36–44	hotbar

Note that this is different from inventory items stored in a player.dat file. This may help: https://gist.github.com/459a1691c3dd751db160

Crafting table

This is the window that is opened when the player right-clicks on a workbench.

Slot range	Description
0	crafting output
1–9	3×3 crafting input (1 + x + 3 * y)
10–36	main inventory
37–45	hotbar

Chest

This is the window that is opened when the player right-clicks on a single chest block.

Slot range	Description
0–26	chest
27–53	main inventory
54–62	hotbar

Large chest

This is the window that is opened when the player right-clicks on a double chest block (two adjacent chest blocks).

Slot range	Description
0–53	chest
54–80	main inventory
81–89	hotbar

Furnace

Slot range	Description
0	ingredient
1	fuel
2	output
3–29	main inventory
30–38	hotbar

Dispenser

Slot range	Description
0–8	3×3 dispenser contents (x + 3 * y)
9–35	main inventory
36-44	hotbar

Enchantment Table

Slot range	Description
0	item to enchant
1	lapis lazuli slot
2–28	main inventory
29–37	hotbar