Inserters

For the common yellow electrical inserter, see Inserter.

Inserters are devices which are used to move items over short distances. When placed, they have a fixed direction. They can move items from behind and place them in front of them. By doing this, they can move items from one transport belt to another, but also extract items from—and insert items into—machines or storage devices.

Types of inserters

Burner inserter	The only fuel-powered inserter.
Inserter	The standard electrical inserter.
Long handed inserter	Capable of inserting and removing items from a greater distance.
Fast inserter	Much faster than the inserter.
Filter inserter	Variant of the fast inserter that can filter items by type.
Stack inserter	As fast as the fast inserter but can move many more items at the same time.
Stack filter inserter	Variant of the stack inserter that can filter items by type.

Mechanics

Inserters will:

• Pick up items off the ground, off of a Transport belt, or from any object that has storage space, including chests, furnaces and assembling machines.
• Place the item onto the ground, onto a transport belt, or into any object that has storage space.
• Run at slower speeds when starved for energy.
• Pick up as many items as their stack size allows at once, if they do not have to wait too long to pick them up.

Inserters will not:

• Pick up any items that can not be inserted into the adjacent entity.
• Pick up items to place into an entity with a full inventory.
• Place more than one item at a time onto the same ground tile.
• Place items into an entity that can not hold them, for example due to filtered or limited slots.
• Fill up the entire target inventory of boilers, nuclear reactors,s, furnaces, and turrets.

If two or more inserters are picking up from the same tile, the inserter who can grab the items the fastest will grab them first. Besides faster inserters, this favors inserters taking from the inner lane of a transport belt.

Insertion limits

Depending on where an inserter is moving items, it does not always fill up the entire target inventory. This allows other inserters taking from the same transport belt to pick up their share of the items. For example, if a boiler has 5 or more items of fuel in it, an inserter will not insert additional fuel. This allows the other fuel to travel further down the transport belt. When the fuel drops below 5 items, the inserter will resume inserting fuel, up to the limit of 5 items.

Entity	Item type	Automatic insertion limit
Boilers, burner inserters, furnaces, and nuclear reactors	Fuel	5
Gun turrets	Bullet Magazines	10
Artillery turrets	Artillery shells	5
Assembling machines, furnaces, centrifuges, chemical plants, and oil refineries	Items needed for the recipe	The ingredients for 1 craft additionally to ingredients for the number of crafts that can complete during one full inserter swing; but at least the ingredients for 2 crafts and at most the ingredients for 100 crafts.
Labs	Science packs	Double the number of science packs needed for one research unit.

An inserter that has a higher inserter capacity bonus than 1 can overfill the target building, due to the inserter picking up a higher amount of items than needed. Overfilling can also occur if multiple inserters are used to insert items into one building.

Inserters and transport belts

Transport belts have two lanes on which items can travel. Inserters only place items onto one side of the belt, either the far side from the inserter's perspective or if the belt is going the same or the opposite direction as the inserter the right side from the belt's perspective.

Inserters place the item on the furthest lane. If a belt is in the same orientation as the inserter, the item will be placed on the right-hand lane, from the belt's perspective. If the item is placed on a corner piece, it will be put on the inside of the curve, regardless of orientation.	Inserters prefer taking items from the nearest lane. If the nearest lane is empty, the inserter will take from the far lane. If a belt is in the same orientation as the inserter, the inserter prefers taking from the left lane, from the belt's perspective. If the left lane is empty it will take from the right lane.

Potential issues

Inserters may have problems picking up items:

• From very fast belts, because the items are moving too quickly.
• From the entry or exit of an underground belt (because the time they have to pick up is shorter)
• From turning belts if the item is on the inside of the corner

Power usage

• Electric inserters drain energy even when they are not moving, as idle power
• The amount of energy used is the same for every turn
• The burner inserter does not drain energy when idle, but uses more energy when it is active.

Inserter speed

Type	Rotation-speed (turns per Game-tick) Extension-speed (Tiles per Tick)	Turns per Game-second Tiles per Game-second	Game-second per full turn Game-seconds per Tile	Ticks per full turn Ticks per Tile
Burner inserter	0.01 0.0214	0.59 1.284	1.7 0.833	102 76
Inserter	0.014 0.03	0.83 1.8	1.2 0.56	72 54
Long handed inserter	0.02 0.0457	1.15 2.742	0.867 0.416	52 36
Fast inserter Stack inserter Stack filter inserter	0.04 0.07	2.31 4.2	0.433 0.238	26 24

Rotation Speed

Convention: 2π rad = 100% of a circle rotation = 1 turn (or one full rotation).

Note: an Inserter doesn't always need to make full turns. When grabbing from a transport belt, it is slightly faster when grabbing items from the closest lane.

Extension Speed

The extension-speed is normally not visible (only when compared to other inserters), but there are measurable speed differences when taking - for example - from the near or the far side of a belt. Also Some mods can alter the pickup and drop locations of inserters, making this stat more relevant.

Inserter Throughput

The following is based on experimental data gathered in version 0.15.

Inserter throughput between chests and other stacks is a simple function of stack size and arm speed:

n = Stack size

t_arm = Time to move the arm back and forth

Time per item = t_arm / n

Throughput (items/sec) = 1 / Time per item = n / t_arm

When moving items to or from belts, the time to pick up or put down items also becomes a factor:

t_item = Time to pick up or put down one item

t_cycle = Time to complete an arm cycle = t_arm + n*t_item

Time per item = t_cycle / n = t_item + t_arm / n

Throughput (items/sec) = 1 / (t_item + t_arm / n)

Note: Before 0.15.14, inserters were 1-4% less efficient when moving items from south to north.

Chest to chest

Type	Arm cycles per second	Items/second at capacity bonus level (stack size)
		No capacity bonus		Capacity bonus 2		Capacity bonus 7
Burner inserter	0.59	0.59	(1)	1.18	(2)	1.76	(3)
Inserter	0.83	0.83	(1)	1.67	(2)	2.50	(3)
Long handed inserter	1.15	1.15	(1)	2.31	(2)	3.46	(3)
Fast inserter Filter inserter	2.31	2.31	(1)	4.62	(2)	6.93	(3)
Stack inserter Stack filter inserter	2.31	4.62	(2)	9.23	(4)	27.70	(12)

Chest to belt

Throughput going from chest to belt depends on how full the belt is. An inserter will not put down an item on a belt that have items back-to-back (aka full compression) - it waits until there is a gap. However, if the gap is narrower than the item then the items upstream on the belt will stop to make room for the item being inserted.

In these measurements inserters move items onto an empty perpendicular belt. Values are given for the stack sizes at three different capacity bonus levels.

Type	Items/second at capacity bonus level (stack size)
	No capacity bonus				Capacity bonus 2				Capacity bonus 7
Burner inserter	0.59	0.59	0.59	(1)	1.10	1.13	1.14	(2)	1.53	1.62	1.67	(3)
Inserter	0.83	0.83	0.83	(1)	1.52	1.58	1.60	(2)	2.05	2.22	2.31	(3)
Long handed inserter	1.15	1.15	1.15	(1)	2.03	2.14	2.18	(2)	2.65	2.95	3.10	(3)
Fast inserter Filter inserter	2.31	2.31	2.31	(1)	3.64	4.00	4.14	(2)	4.29	5.14	5.63	(3)
Stack inserter Stack filter inserter	3.64	4.00	4.14	(2)	4.71	6.15	6.86	(4)	5.90	9.60	12.20	(12)

To calculate the throughput for Stack inserter and Stack filter inserter at any capacity level, you can use these linearly fitted factors with the belt/chest throughput formula above:

Type	Transport belt		Fast transport belt		Express transport belt
	t_item	t_arm	t_item	t_arm	t_item	t_arm
Stack inserter Stack filter inserter	0.142	0.292	0.073	0.360	0.049	0.384

See the source spreadsheet for the corresponding factors for the other inserter types. Their errors are generally well below 1%.

Belt to chest

When picking items from a belt, many more factors come into play besides belt fullness:

• How fast the items move (i.e. if they are queued up on the belt or move at belt speed).
• Whether the belt is perpendicular to the inserter or approaches it head on.
• Whether items are on the near or far lane of a perpendicular belt.
• Whether the belt turns or not, and whether the items are in the inner or outer side of the bend.
• If the belt is an underground entrance or exit. This shortens the time items are visible to the inserter for pickup.
• All sorts of intricate timing factors between the inserter and the items on the belt, since the game simulates the arm homing in on every item.

The test setup used below is with an inserter taking items from a perpendicular belt with items on the far lane only. The belt is fully compressed and timings are both for items that move at full speed and queued up as much as possible. Values are given for the stack sizes at three different capacity bonus levels.

Type	Items/second at capacity bonus level (stack size)
	No capacity bonus					Capacity bonus 2					Capacity bonus 7
	Items at belt speed			Items queued up		Items at belt speed			Items queued up		Items at belt speed			Items queued up
Burner inserter	0.56	0.56	0.51	0.65	(1)	1.11	1.07	0.98	1.18	(2)	1.43	1.54	1.43	1.75	(3)
Inserter	0.83	0.74	0.77	0.90	(1)	1.57	1.48	1.45	1.62	(2)	2.00	2.11	2.07	2.40	(3)
Long handed inserter	1.16	1.11	1.11	1.22	(1)	2.22	2.22	2.11	2.31	(2)	3.08	3.08	3.16	3.33	(3)
Fast inserter Filter inserter	2.22	2.22	2.14	2.40	(1)	4.17	3.81	4.00	4.29	(2)	5.71	5.45	5.46	6.21	(3)
Stack inserter Stack filter inserter	4.17	3.81	4.00	4.29	(2)	6.67	6.67	6.15	6.67 / 7.50 / 7.74 *	(4)	6.67	10.00	12.00	6.67 / 11.61 / 13.58 *	(12)

*) Throughput for basic/fast/express belt.

Since there are many more factors involved, these measurements exhibit a more complex pattern than chest-to-belt.

• Boldface cells show for which belt each inserter has the best throughput on each bonus level when items move at belt speed. Higher speed belts mean that inserters have to work harder to catch the fast moving items. The effect is most noticeable for slower inserters and smaller stack sizes.
• When items are queued up the belt type hardly matters, so there is only a single column for that. The exceptions are the stack inserters - for basic transport belts it's the belt that sets the limit for stack sizes above 4, and there is also a notable difference between fast and express belts.

Here are linearly fitted factors to get the Stack inserter and Stack filter inserter throughput at any capacity level, by using the belt/chest throughput formula above:

Type	Transport belt		Fast transport belt		Express transport belt
	t_item	t_arm	t_item	t_arm	t_item	t_arm
Stack inserter Stack filter inserter	0.045*	0.403*	0.063	0.387	0.049	0.416

*) Since the belt is the limiting factor above stack size 4, these figures are only accurate up to that size. More than that and the throughput is fixed at 6.67 items per second.

See Also

• Electric system
• Belt transport system
• Inserter capacity bonus (research): Inserter moves more than an item per turn.