Bulk inserter

Bulk inserter is an inserter building whose stack size is increased by the Inserter capacity bonus research. By default, it picks up 2 items at a time, and each researched level raises the total stack size according to the technology tier. The stack size can also be overridden in the inserter settings, but the selectable maximum is limited by the highest Inserter capacity bonus level currently unlocked.

The progression is:

• no Inserter capacity bonus: 2
• bonus 1: 3
• bonus 2: 4
• bonus 3: 5
• bonus 4: 6
• bonus 5: 8
• bonus 6: 10
• bonus 7: 12

This means the early research levels increase the stack size by 1 each, while later levels increase it by 2 each. As a result, the bulk inserter becomes significantly more efficient once the higher Inserter capacity bonus technologies are available, especially when moving large item stacks between belts, machines, and buffers.

Because the stack size is tied to research, bulk inserter performance scales directly with the player’s science progress. If a specific item flow is needed, the stack size override lets the player reduce the amount picked up per swing without being able to exceed the researched cap. This makes it possible to tune inserter behavior while still benefiting from later research upgrades when the larger stack sizes are desirable.