Belt Throughput Calculator for Factory Games

When output is slow yet belts keep moving, you can see why a lack of understanding leads to so many mistakes in planning. Belts carry items along which makes it look like there is plenty of movement, even as they fill up and machines downstream is idle. Speed does not equal capacity.

Your supply chain have limits governed by things like insertion rates, lane compression, and the shape of splitters. All this change as you ramp up from mining ore to chemically synthesizing compounds. After entering the number of inserters/belts you want to use, the calculator (above) crunches numbers for you. No more guesswork with coefficients.

How to Make Your Factory Work Better

Before you get to the tool, understand what those numbers mean so that you can build layout in advance. The problem isn’t typically just the speed of belts. Usually it’s how many items you have per lane. How many items can be stuffed onto each lane without leaving gaps between them? You’ll notice that they can’t all fit directly next to each other. There must be some breathing room, some compression, due to items needing to shift as they turn corners/merge.

Unbalanced lanes will cause jams. One lane might get backed up while the other has lots of open slots running empty. Even though both lanes is still moving at max speed, this halves the capacity.

The stats for belts don’t account for inserters. A fast inserter process double what a basic one does, provided there’s somewhere to move things to and some chest to grab from. Want more flow? Pile on inserters with arms. But they’ll idle if placed inefficiently or if they run out of resources. You have all the mechanical power required to fuel the belt. But because they’re not timed properly or can’t quite reach, you only get half the output. That’s where most folks miss out. They treat the symptom instead of fixing the bottleneck.

A lot gets lost when things is split. The more often you split a bus to distribute it among multiple production lines, the more you lose throughput. If one branch sucks it up too fast, it will starve out the others. The slower items has to synchronize with each other, slowing them down. This requires balancers which add both space and length requirements. The calculator allows you to enter the number of stages and the percentage you expect to lose because of this. A straight line has no loss. But a complicated network of merges and taps may end up shedding five to ten percent of your theoretical maximum before reaching your machines.

Belt stacks multiply capacity not just by lane width, but also by the number of items per stack. So if you’re storing modules in tight space or offloading trains into a bin, they’re great, assuming your inserters can manage those bigger bundles. Stacking belts on slow arms forms a bottleneck at the loading point, though. Use it to compare your belt capacity against the inserter’s maximum limit to find the bottleneck.

When designing a megabase, don’t only count belts: Count merges, transitions, and feeding points. Include a buffer margin for temporary demands (e.g., maintenance down-time) as well. Better safe than sorry, better should of have a little extra capacity than run short and rebuild a quarter. The page’s tables of reference provide standard benchmarks; however, your real-world figures will depend on how well you build it.

It’s not about going fast. It’s about going right. Smooth, compressed flows are always better then high speed chaos. Respect the limitations of your splitters and inserters and stop trying to fight the gaps. And then the entire factory begin breathing again.