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I've been playing Factorio quite a while now, but I've never really gotten into modules much. They don't seem to really add anything, when you look rationally at the math.

For example. Lets say I am producing green circuits, and I want to increase production. If I pop in 4x speed3 modules in a machine and surround it with beacons (lets say 6) with 2x speed3 modules, I can now produce 4*3*50=600 + 6*2*50/2 = 900% faster. But it also takes 1260% more power.

If I were to increase production by simply adding more machines, I could get 900% increase by adding 9 more machines, and it would only cost me 900% increase in power. Basically with modules I would be "paying" an extra 360% power for no benefit.

So why would I want to spend more power than I need to? I cannot see any way around the basic math here, and I suspect modules are "for suckers", and for people who like the additional layer of complexity. There is also the fact that modules are expensive.

If I came to your home and told you "Hey, I can install this gadget in your coffee machine so it will make your coffee 900% faster, but it will take 1260% more energy!" I assume most rational people would just throw me out. But not in Factorio.

Now, I can see some instances where they can have a true use. For example:

Efficiency modules that reduce pollution and energy. Not incredibly useful, but still a usage that actually works as intended.

Getting more oil. Adding speed modules to oil jacks. Since oil wells are infinite, it can be a way to create a viable oil source from a depleted well.

Technically you could do the same for any ore, but they are 1) not infinite, 2) more abundant. You could add speed modules to an ore field, but then, you could just find another field and double production without spending more power. You could add productivity modules to squeeze more ore out, but it would also slow down the mining. Again, on an infinite map, you could just find another field and modules are useless again.

Productivity modules could save you precious resources, if you are particularly low on something. Again, on an infinite map it should not be an issue, but at least it is an effect that DOES something, as opposed to just pretend to do something.

So am I wrong here? I see very experienced Factorio players like Nilaus talk about how modules are ESSENTIAL for the mega base. But I just don't see it. Unless space is a limited resource. But again... infinite map?

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  • "4*3*50=600"? Where the heck did you take that 3 from? It's 4*50=200. Commented Dec 1, 2023 at 12:27

10 Answers 10

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Something none of the answers have really spelled out yet is the true effect of combining speed modules with productivity modules.

The effects

The key observation is that the effects stack additively. This means that, e.g. an Assembler 3 with 4x Productivity 3 modules will produce 40% more items per input, while working at 40% speed (-60% malus). And consuming 320% more power for 420% total, but more on that later.

Meanwhile a single Speed 3 increases speed by 50%. Your assembler has all its slots taken up by Prod mods, and beacons only transmit half the effect, so it's 25% per module. Place four beacons in range of your assembler, and the modules give it a +100% bonus. Summed with the malus from the prods, it totals 140% speed. While also having 40% extra output (for free).

The result is that you need way fewer machines to make way more output with way less input.

Let's visualise it.

  • Here's a calculator output for one yellow belt of red circuits. Notice how it needs 2 input belts of iron, 5 input belts of copper, and 114 assemblers total (plus miscellanea for oil products). And uses 107 MW of power.
  • And now here's the same assembly line, heavily moduled (with four speed-3 beacons in range of each assembler): we're using 36% as much copper, ~36% as much oil, 45% as much iron, and only 31 assemblers. And the assemblers themselvers are only using about 22% extra power (this doesn't take into account beacon power draw, but again, more on that later).

But why bother?

The effects are absolutely drastic for large-scale builds.

The poster child of the effect of modules is probably rocket science, which I will leave for you to peruse yourself in

What does this mean? Everything is smaller and easier. Sure, you can always just build a larger factory. Place 10x more assemblers and furnaces, 3x more miners (on 3x more patches), and get the same output. But why not place 3x more miners, then only 3x more assemblers and furnaces, and get 3x the output?

Because space is free (and infinite), but logistics aren't. Your items need to get from point A to point B, and your factory has a large amount of different processing lines all feeding into each other. It's just that much more effort to connect 10x bigger assembly lines to each other. It's just wasting your play time with needless complexity. Not that it trivialises the game or anything: if you want the extra logistical complexity, just build even bigger while reaping the advantages of modules!

Some of the other answers have mentioned UPS/lag, which becomes relevant for pushing the game to its limits (or if you're playing on a weaker machine). Beacons do not take any processing power - they just apply an attribute to nearby machines - so being able to build the same factory with 5x-10x fewer machines means you get that much less lag. Or conversely, you can build a 5x-10x bigger factory before the game slows down.

A note on mining speed, late-game

Mining productivity research essentially gives you free ores per ore. It's also the only infinitely repeatable research whose costs grow linearly rather than exponentially, so it's realistic to reach very high levels when going for endgame builds. At minining productivity 10 you have a 100% bonus, meaning two ores per ore; at mining productivity 100 you have a 1000% bonus, meaning you get ten free ores for every ore mined (or 11 ores per ore).

At those levels, ore patches start lasting for a very long time indeed. And so it starts making sense to add speed modules to miners, to get more output from the mine. It's not gonna run out for dozens of hours anyway, and it's just faster to stick some modules than it is to run out, find another patch, lay more miners, lay your train tracks to it, hook it up to your train schedules...

But what about power?

Beacons take a lot of power to run. Especially if you're going to be building a factory containing thousands of the things.

Here's the thing, though: power generation in Factorio is really cheap and easy. Usually, a power plant will take up about 5% of a typical factory*. So think of it this way: it's much easier to quadruple your power production while building a 5x-10x smaller factory, than it would be to quintuple your entire factory. If you were willing to put down 1000 extra assembly machines and 2000 extra furnaces - it's much much easier to, instead, simply plop down 8 extra nuclear reactors and the few dozen heat exchangers and turbines around them.

Oh, and pollution is worth mentioning here. Beacons don't generate pollution either, so funnily enough despite both speeds and prods having large pollution penalties, because you'll be using just that much fewer machines, I don't remember the maths but I think moduled factories are either actually greener than unmoduled ones, or at the very least barely any more polluting.

*The elephant in the room here is solar power, which is notorious for requiring vast tracts of land to get covered in solar panels to give reasonable outputs. But here's the thing, you need so many solar panels that you're probably going to automate its construction (with expandable roboported blueprints) already anyway. And solar fields simply... exist; they require absolutely zero logistics to set up, once you've got the blueprint designed and kicked off - so in their case, space really is infinite and building large is completely free.

But what if I'm not building giant endgame bases

Well then modules aren't essentials. You can easily launch the rocket without ever touching a module.

The tl;dr is that modules drastically cut down the time and effort to build huge megabases; and make it possible to build far bigger ones without lagging than could be done otherwise. But they're definitely not necessary or essential when building at small scales, like just enough to launch one rocket in vanilla.

What about efficiency?

I've focused this answer on speed and prod, because ultra-end-game, these are the ones that matter, and they are the ones that are truly essential. Efficiency is mainly useful in other scenarios - namely, when you want to reduce pollution. But when you do want to reduce pollution, they're absolutely cracked - the maximum you can get on any machine is -80% power consumption (and pollution), and you can easily reach that on most machines with just tier 1 greens.

As a result they can be a good candidate for sticking into miners, which normally generate a huge amount of pollution, provided you're not ultra end game yet and don't have huge mining productivity bonuses (at which point you'll be wanting to switch to speed 3s as mentioned earlier). But in general, tier 1 greens are a very cheap way to cut down your pollution and power consumption if you ever need to for any reason.

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  • 4
    You might slightly improve this great answer by mentioning that beacons don't just cover one machine, so the beacon:assembler ratio is closer to 1:1 than the 4:1 often mentioned in Prod + Speed examples. Commented Apr 9, 2023 at 21:28
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    +1 for the key "space is free (and infinite), but logistics aren't". When building a centralized 10K SPM base, train logistics are non-trivial even with productivity modules all the way cutting down material requirements by 3x or 4x. Even with nuclear fuel, maximized breaking distance and good signalling you still need to optimize your train network to minimize crossings (or make them efficient). And of course unloading the trains (in vanilla) at that scale is non-trivial. That 128x128 balancer requires quite a bit of material, after all. Commented Apr 10, 2023 at 9:49
  • With regard to efficiency modules: one excellent reason to use them is playing on a "Death World" (ie, with bugs settings cranked up to the max). Commented Apr 11, 2023 at 7:19
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The most important module for most players is the productivity module, because it increases the output you get per input. This means that for a given raw material production rate, you can produce more processed items with modules than without them. This effect is particularly strong on recipes that require ingredients that are late in the production tree and represent large amounts of raw materials, such as rockets, labs, and satellites. As other answers have noted, speed beacons are primarily useful to offset the speed loss from productivity modules. Efficiency modules are more niche, and are primarily used on death worlds to minimize pollution to avoid aggroing the biters. Power is generally not a concern; it is fairly easy to over-produce power by the time you get to modules.

In addition, as this reddit post describes, speed modules are actually fairly efficient in terms of increased energy consumption per item produced, because the energy consumption penalty is per unit time, but the machine is producing more items in that same amount of time. In the limit, as that post says

Furthermore, stacking speed modules has an even more dramatic effect, 4x Speed 3 Modules, with a combined +200% speed and +280% consumption, only increase energy per item by +27% - a mere 10% of the +280%.

The Module wiki page also says this about speed and productivity modules:

There is however synergy between productivity modules and speed modules, productivity modules reduce crafting speed which lowers the production rate of items and increases the energy consumed per item, the speed bonus from speed modules increases production rate of items and lowers the energy consumed per item - in fact when dealing with productivity modules, the reduction in energy consumption from the increased speed from speed modules can be greater than the increased energy consumption. For detailed calculations on the synergy between productivity modules and speed modules refer to this discussion as well as this warning.


At megabase scale, things change because the main concern becomes UPS (updates per second). This number generally stays at 60 for normal play, but if there is a very large number of active entities on the map, it can decrease. That can make the game more unpleasant to play, and the decrease in the rate at which the game plays can offset increases in production. Modules and beacons maximize the amount of production you can get per active entity, so they are essential to building at megabase scale.

At megabase scale, when trying to minimize active entities as much as possible, it is more worthwhile to use modules and beacons on earlier intermediate products, and as a result you also get the benefit of compounding productivity. For example, looking at one line through a production tree:

  1. With productivity modules in a rocket silo, you need ~30% less of all input items per rocket.
  2. With productivity modules in blue circuit production, you need ~30% less red circuits to make enough blue circuits to launch a rocket.
  3. With productivity modules in red circuit production, you need about ~30% less green circuits to make enough red circuits to launch a rocket.

So, using productivity circuits in that whole chain means that you need 0.7 * 0.7 * 0.7 = 0.343 times as many green circuits to launch one rocket as you would need with no productivity modules.

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  • So you are talking late game products, and computer power. I still don't get the ESSENTIAL side of it. Sure, 30% bonus to expensive products is nice, but is it game changing? You may be right, but I was looking for numbers.
    – TLP
    Commented Apr 8, 2023 at 21:12
  • 1
    I added some more information about power consumption and about productivity compounding, with numbers. Commented Apr 8, 2023 at 21:54
  • @TLP think about this: if you put a couple of Prod modules in the rocket silo, you only need to make 70 parts to launch a rocket. That's a huge difference for relatively little investment. Research is also a good candidate for them you literally research at 1.3x speed.
    – yesennes
    Commented Apr 11, 2023 at 15:46
  • @TLP It compounds. Prod in science assembly and labs gives you a 68% bonus
    – Caleth
    Commented Mar 1 at 15:17
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Because power logistics is easy. Throw power on the net, and it's anywhere you need it to be, instantly, as much as you want.

You don't need more belts, bigger belts, faster belts, trains, tunnels, splitters. You throw it on the net, and it's done.

Copy paste some solar+battery arrays, bots install it, and you got your power. Done.

Now compare that to copy-pasting factories. Especially with oil. In comparison, that's a lot of work. And the belts don't just scale as easily, nor do the trains.

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On power efficiency, modules never beat building more machines - but power is cheap and easy to scale up with no regard for location, while factories and belt networks need to be more carefully planned.

Modules stack additively, so four speed module 3 gives +50% * 4 = +200% = 300% speed and +70% * 4 = +280% = 380% power consumpton.

So you have the choice between boosting 1 machine with modules to 3x speed and barely 4x power consumption, or building 3 machines to get 3x speed and 3x power consumption. The trade-off is having to triple the complicated part of your factory, or copy-paste some of your solar arrays a few more times.

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  • You could just copy paste your production array a few more times too. Or? That does not explain how it is considered "essential" for mega base construction. Not a bad argument for adding modules to existing buildings, but what about beacons? Have you seen some of the beacon modified stuff where they use more beacons than assembly machines?
    – TLP
    Commented Apr 8, 2023 at 15:59
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It's tricky to look at the benefits of a module vs an extra production building in a vacuum. Yeah, the map is infinite, and the resources are infinite, but let's look at what happens when you decide to add zero modules and compensate by just building more assemblers:

  • Now your base is bigger, so you need more belts, inserters, roboports, cables, etc
  • Your bots need to fly further, so you both need a larger cloud of them and have more overhead & waiting time whenever something changes
  • Your base is bigger, so you need more walls, more turrets to cover it, more ammo/power to feed them
  • Also you make more pollution, so you need even more turrets everywhere to deal with the larger waves of bugs
  • Also you need more patches being mined, because your base uses more resources (for both your extra factories since you don't have productivity boosters and for all the extra infrastructure you need to build)
  • This means you need more rails, more trains, more mines, and then even more walls and turrets to protect all of them (and it produces even more pollution)

And of course, you need to actually manage all these things, so it's also additional overhead on you as the engineer to set all of it up.

That is not to say you can't build without modules, but I'm assuming the really experienced guys tried both and realized that all the little bonuses from modules, including the not so obvious one, really do add up to more usefulness than just slapping down more assemblers.

I'm not super good at Factorio, but from personal experience, the first time I decided to use modules and put Efficiency Modules into every mining outpost I had, pollution there dropped by 80% and bug attacks went from "constant annoyance" to "almost non-existent". The time and resources saved by not constantly having to think about protecting or repairing them was huge, and that wasn't even a mega-base or high level modules.

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  • I'm not sure you added anything new, but thanks for your answer.
    – TLP
    Commented Apr 8, 2023 at 21:10
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Speed modules are mainly used to offset speed penalty from productivity modules. The benefit of productivity modules is huge, as they apply on all the prereq of what you are building. Prod module in rocket silo and labs --> you need to build less of everything. This table sums up payoffs : https://factoriocheatsheet.com/#productivity-module-payoffs

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  • I hear what you are saying, but still, I don't see any numbers contradicting mine. 30% extra products for 310% more power, on maps with endless resources still makes me think I would be better off just adding more production buildings.
    – TLP
    Commented Apr 8, 2023 at 16:06
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Since you used the word "essential" in a comment: There is nothing essential about modules, they are totally optional in all stages of the game. If all the positive points listed in this and other answers are low on your priority list, or not on it at all, then you personally won't get benefits from modules. There are people playing without modules as a matter of fact, and that is a perfectly valid play-style, even for large factories.

That said, in my factories, modules are excellent in these aspects:

  • They allow me to achieve the same amount of output with less space usage.
  • (Totally subjective) they give me another puzzle to solve.
  • They reduce the amount of source items (for intermediate recipes, not finished products, obviously).

The first part is mostly relevant (to me, subjectively) because I love compact(er) designs; and secondarily because this then requires less of the supporting items (belts etc.).

The second part is important to me because I have done soooo many factories; there is little challenge in clicking together yet another line with only assemblers. But optimizing beacon layouts seems to be fun for me every time. I play primarily for fun, so the actual activity I am doing is meaningful as well, not only the raw maths.

But the last one is the big one. By using productivity and speed modules, you reduce the required source materials not just for this particular assembler, but all the way down to raw materials. If you have productivity modules on, say, the rocket silo, then all those savings go down recursively through the whole production line. And of course also for the productivity modules on the items before that. This effect adds up enormously, and you have to build much fewer mining outposts, less trains, less belts, less congestion, etc. etc.

For context, I have finished several 1kspm vanilla factories, have played most of the big mods out there (i.e. full Pyanodon, SeaBlockPack, Space Exploration and many more), and am currently in the finishing touches of a vanilla 10kspm (which would be nearly impossible without modules, at the very least psychologically). I totally get where you are coming from (for example, I had given myself a limit of "no modules" at all in my SeaBlockPack just for fun), but if your maths says that they don't have a benefit, then the math isn't quite right.

To make sure, you can fire up one of those in-game or website-based recipe calculators, click together a complete recipe for the rocket with all ingredients down to raw ores, and then compare "no modules" vs. "full productivity + speed beacons" (you can use an average of 8 beacons per assembler if you're not sure). You will most definitely see a noticeable difference.

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About modules I have a specific approach linked with some OCD on my side:

Power modules : reduce biter attacks

I play on peaceful and the few times I played "normal" (to unlock some achievements for example) I used a lot of green modules to reduce pollution and make the biters less angry. It goes slower? Nah I'm not in a hurry.

Production modules : less ore depletion or saving rare ore/components.

In short: rocket construction, kovarex enrichment or very expensive parts (blue circuits). I know it won't do much of a change especially with level 1 modules but in my head I know that free item costed nothing but a little more electricity and time instead of resources.

(sidenote, solar is infinite so I personnaly don't consider electricity as "expensive" and simply adapt)

Speed modules : gimme part quick!

When I see machines clogging that could go faster and I want things to arrive quicker on my belts I use speed modules, especially when idleing.

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Efficiency Modules

reduce power consumption and pollution. They are cumulative, but the max reduction is 80%, i.e. 20% pollution will remain.

Of these effects, energy tends to be quite irrelevant, because by the time you research modules, you have access to clean power, and building more power is cheaper than modules.

That leaves pollution. Pollution drives the intensity of biter attacks, and is a major driver for their evolution. Equipping your factory with efficiency modules may increase its construction cost, but it will allow to produce over twice as quickly at the same pollution level (or produce at the same speed at less than half pollution).

Productivity Modules

produce more output at greater pollution and much less speed. They make a manufacturing step need more assembly machines, and cause these to emit much more pollution per product made. However, they make more products out of the same quantity of raw materials.

Productivity modules are therefore best used where expensive raw materials flow through a cheap (i.e. quick) production step. A prime example is assembling electronic circuits (whose 0.5 second manufacturing time means that the pollution of the assembling machine is negligible compared to the pollution emitted by extracting and refining the raw materials), or sulfuric acid. Some advanced science packs are also prime candidates.

However, productivity modules remain a very situational pick. The main problem is that their disadvantages combine multiplicatively. As the assembly machines grind to a near halt due to the speed debuffs, the amount of assembly machines, and the pollution caused by each machine, explodes.

That changes with the invention of the beacon, and that brings us to

Speed Modules

which allow to increase the speed and energy (and therefore pollution) of an assembling machine. As you rightly observe, speed modules are mostly useless if used on their own.

But what happens if we combine modules of different types? After all, beacons allow us to add a lot more module effects to an assembly machine than its slots would seem to indicate.

Adding more than 3 efficiency modules is useless, because we hit the maximum reduction of 80%. But if we add a speed module to increase speed and energy, and then further efficiency modules until we hit the max reduction again, we can produce with increased speed at the same, minimal, energy and pollution output, reducing the pollution per item :-)

Likewise, as described above, adding several productivity modules causes a prohibitive slowdown of the machine. But if we add speed modules to compensate, we can have a machine that produces more output at the same speed, and if we add sufficient efficiency modules, at the same, minimal pollution output.

Put differently, speed modules are for creating synergies once beacons allow you to bring many effect sources to bear. The disadvantage of such a setup is of course the cost of all those modules, and the electricity consumption of all those beacons. But the benefit is a factory that produces far less pollution per item made.

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First of all, let's get the obvious out of the way. You've probably read https://wiki.factorio.com/Module#Usage_tips but to quickly summarise:

  • Filling devices with productivity modules is recommended when resources are scarce.
  • Filling devices with efficiency modules is recommended for electric furnaces as these use a lot of power.
  • (And as you stated, speed modules on oil)

Outside of these scenarios, all three types of module are a temporary option, a quick and dirty fix for a production imbalance or power consumption imbalance. They have situational benefits. They are not a gimmick, but they are also not a permanent solution, and it is easy to fall into a bad habit of using them.

You are right to say that modules are not ESSENTIAL. If you need production of an item to be improved and to remain scalable, the permanent solution is more mines/assemblers/belts, not modules. This does require you to have materials, space and a plan including transport links.

For some number crunching, see https://forums.factorio.com/viewtopic.php?f=5&t=5705. If, in your opinion, this does not add anything to previous answers, then please clarify your question OR mark one of the previous answers as the solution so that you don't get more and more answers all blindly saying the same thing.

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  • "bad habit of using them" Yes, let's tell people how they must play this game. Commented Dec 1, 2023 at 12:37

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