Belts, Inserters, and Logistic Bots
The three ways material moves around your factory: belts for steady high throughput, inserters to load and unload, and logistic robots for messy low-throughput delivery.
Almost everything in Factorio comes down to moving items from where they are made to where they are needed, and the game gives you three tools for it: transport belts, inserters, and logistic robots. They are not interchangeable. Belts move a steady stream cheaply, inserters bridge belts and machines, and robots handle the scattered, low-throughput deliveries that belts handle badly. Most of a good factory is choosing the right one for each job, and most beginner spaghetti comes from leaning on belts for everything. Getting comfortable with all three is what lets your factory scale past the early game.
Belts
Transport belts move items along a line, and they come in three tiers shown by color: yellow is slowest, then red, then blue is fastest. A yellow belt moves 15 items per second, which is the number most smelting and mining ratios are built around. Belts carry two lanes, so a single belt can run two different items side by side, and learning to manage lanes is part of building a tight bus. Throughput is the whole point: a belt delivers a constant rate, so you size your smelters and assemblers to fill or drain a belt cleanly.
Inserters
Inserters move items between belts, machines, and chests, and nearly every machine needs one to load it and another to unload it. The variants matter. Long-handed inserters reach one tile farther, which lets them grab from past a chest or across a gap. Filter inserters can be set to move only specific items, including by a circuit signal, which makes them the tool for sorting a mixed belt or pulling one product out of a recycler’s output. Matching inserter speed to belt speed is a quiet source of throughput: a slow inserter on a fast belt is a bottleneck you may not notice.
Logistic robots
The logistic network is a system of logistic containers served by flying robots, all within a roboport’s range. Provider, requester, storage, and buffer chests, plus the landing pad in Space Age, let robots automatically deliver requested items. Robots shine at the messy, low-throughput delivery that belts do poorly: topping up a mall of assemblers that each need a trickle of many parts, or ferrying items across an awkward layout. They are unlocked mid-game, in the utility-science era, and they cost power and bot frames to run.
Belts for high steady throughput, bots for low scattered throughput. Use bots to deliver a hundred different parts in small amounts, and belts to deliver one part by the thousand. Mixing those up is where factories bog down.
Choosing between them
| Need | Reach for |
|---|---|
| One item at high volume | A belt, sized to its throughput |
| Loading or unloading a machine | An inserter, speed-matched to the belt |
| Sorting a mixed belt | A filter inserter |
| Many parts, each in small amounts | Logistic robots |
| Crossing an awkward or sprawling layout | Logistic robots |
Watch out for
Robots are not free. Each delivery costs power and there is a limit to how many a roboport network sustains, so do not route a high-throughput main line through bots when a belt would do. Equally, do not hand-belt a mall of fifty assemblers that each want a trickle of parts when a small bot network is cleaner. The skill is reading which job is which.
Related: Trains and Key Ratios.