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Factorio

Assembly Line Ratios

Get Factorio ratios right and a line runs non-stop; get them wrong and it starves half the time — and the maths gets fiddly fast.

Assembly Line Optimizer

2

Assemblers Needed

Input Materials Req/Sec

iron plate4.00/s

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How the numbers are worked out

Each recipe has a crafting time and a set of inputs, and each tier of assembler has its own speed multiplier. The calculator tells you how many assemblers of a given tier you need to hit an output rate, and how much input that asks for further up the chain.

The formula

  • effective speed = assembler speed × (1 − 0.05 × productivity modules)
  • items per craft = recipe output × (1 + 0.04 × productivity modules)
  • assemblers = ceil((target rate × craft time) ÷ (items per craft × effective speed))

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Common mistakes

Belts are usually the first wall you hit. A ratio can be perfectly correct and still stall because the belt feeding it cannot move enough items per second, so compare the belt tier with the input rate before you build the whole row.

More calculators you might need

Rather not run the server yourself?

These tools are free and funded by the two hosting services we run. If you want a server that is already set up, here they are.

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