A stack is the basic element in Factorio to store items. One space in an inventory can hold one stack.
Examples of stacks
- The player's inventory
- Main inventory
- The toolbelt (quickbar)
- Tool, armor, weapon, and ammunition stacks
- Logistic trash slots
- The player's hand (is also a stack)
- Chests: The archetypal example of stacks outside the player's inventory; a chest is basically just a group of stacks.
- Furnace: Burner stack (stone and steel furnace only), input and output stack
- Assembling machines and chemical plants: 1 or more output and 1-6 input stacks, depending on item type being assembled
- Burner-based: Boiler, burner mining drill, burner inserter
- Roboport (filtered for robots and repair packs only)
- Gun turret
How do stacks work?
A stack can store a number of identical items.
The first inserted item determines which item types can be stored. This also indirectly determines how many items can be stored in the stack, as this depends on the item type's maximum stack size.
Only items can be stored within stacks; stacks cannot hold liquids or other entity types.
The number of items a stack can store. Stack size depends on the item; existing stack sizes and (non-exhaustive) examples include (click to expand):
|1||Nuclear fuel, artillery shell, satellite, modular armor, blueprint.|
|5||Locomotive, all wagons.|
|10||Roboport, rocket fuel, artillery turret, atomic bomb.|
|20||Some equipment modules, pumpjacks, steel axe.|
|50||All ores, stone, coal, all modules, electric mining drill, electric furnace, all assemblers, all chests, all inserters, gun turret, laser turret, all power poles including substation, both types of worker robots, solid fuel.|
|100||Iron plate, copper plate, steel plate, processing unit, iron gear wheel, stone brick, all types of concrete, both isotopes of processed uranium, pipe (regular), all belts, wall, landfill.|
|200||Electronic circuit, advanced circuit, all types of magazine, all types of tank cannon shell, copper cable, both colors of circuit wire, all types of science pack except space science pack.|
|2,000||Unique to space science pack, present to allow stacking up to 2 rockets' worth of packs in the rocket silo's single output slot.|
Stacks can be filtered either by default (in burner-type entities, furnaces, roboports, turrets, labs, and other entities that can only accept one or a few item types in a particular slot), or manually by the player (normally set via the middle mouse button / scroll-wheel click, see Keyboard bindings). Manual filtering is available for cargo wagons, the quickbar, and the player inventory, but not for other types of containers (in particular, chests of any type).
This can be used to ensure only one item type goes into the inventory space. Inserters (or bots, where applicable) will not attempt to insert anything except the allowed item type into filtered slots, and manual insertion of other item types by the player is also not allowed unless and until the filter is cleared.
Damaged items (i.e, damaged entities now stored as items) stack with other damaged items (of the same type), but not with undamaged items. When items with different amounts of damage are stacked together, the health of the items is averaged.
Items with durability
Items with durability, such as science packs and repair packs, always stack with items of the same type, regardless of how much durability remains. The durability displayed on the stack is the durability of the first item. After that item is removed from the stack, a stack of items with full durabilities remains. This means that when multiple items with durabilities are stacked together, their durabilities are merged, which can result in a lower overall item count while the overall remaining durability stays the same.
Stack size bonuses
Inserters and logistic robots can be boosted with research to hold and transfer more items, see:
Optionally, the usable space in chests and wagons can be decreased below their default values. Typically, this is done to store a small amount of items in an automated process, without consuming the resources that would be required to fill the entire container.
To limit a container, click the red X at the end of the last stack. Then, click on one of the stacks to set the new limit. The unused stacks will be highlighted red (see right).
When full, inserters will no longer add to a limited container. However, the player is still free to manually place items in the unused (red) slots.
There are some keyboard bindings to quickly handle movement of stacks between inventories, like moving half of a stack to another stack.
In game version 0.10, the number of items which can be stored in a stack changed for most items from powers of 2 to multiples of 10. This change was mainly made because most people find it more intuitive to calculate numbers in a base-10 system.
Example: Before the change, a stack could store 64 iron ore, while after the change it is 50. This created some controversy, as some players preferred the old stack sizes.