How production ratios actually work
Ratios in Factorio look like lore passed between players — 1:2, 1:20:40, and so on. They are not. The common ones fall out of two numbers the game states plainly, and once you can do the arithmetic yourself you stop needing the memorised list. A few chains resist a single ratio entirely, and those are worth knowing about too.
Figures computed from game version 2.1.12, updated 2026-08-04.
The two numbers that decide everything
A recipe states how long one craft takes and how much it yields. A machine states how fast it works. That is the whole input. An advanced circuit takes 6 seconds per craft and yields one. An assembling machine 3 runs at speed 1.25, meaning it completes 1.25 crafts in the time the recipe nominally takes one.
Crafts per second, then machines
To sustain a target rate, first work out how many crafts per second it implies: the target divided by the yield per craft. Then work out how long a machine spends on each craft: the recipe time divided by the machine speed. Multiply the two and you have the machine count.
For ten advanced circuits per second on assembling machine 3: ten crafts per second, each occupying a machine for 6 / 1.25 = 4.80 seconds, giving 48.00 machines. On an assembling machine 2 at speed 0.75, the same output needs 80.00.
Then it repeats, one step up
Each ingredient the recipe consumes becomes the target rate for the step that makes it. Ten advanced circuits per second consume twenty electronic circuits, twenty plastic bars and forty copper cable per second, so each of those stages gets solved with its own figure as the target, and so on until the chain reaches something the game does not craft. That is all a production calculator does: the same three lines of arithmetic, applied repeatedly.
Why modules do not multiply down the chain
This is the part that is easy to get wrong, and getting it wrong makes a calculator quietly optimistic rather than obviously broken.
A productivity bonus applies to the machine it is installed in. If a solver applies it at every depth instead, the bonus compounds: the smelter gets it, the cable assembler gets it again, the circuit assembler gets it a third time, and the reported raw ore demand comes out lower than the game will actually give you.
With +40% productivity in the top machine only, one processing unit per second needs 17.14 iron ore per second against 24.00 unmodded. Compounding the same bonus through every stage would report a considerably smaller figure, and a factory built to it would starve.
If your smelters carry modules too, solve the smelting step as its own query rather than expecting one setting to describe the whole chain.
One caveat about craft times
Only 270 of the 324 craftable recipes state a craft time in the prototype data. The rest omit the field and inherit the engine default of 0.5 seconds — iron gear wheels and copper cable among them. Computing with the default is correct, but it is worth knowing that a figure like “gears take half a second” is an engine default rather than something the recipe itself declares. Where this page quotes a craft time, it is one the data states explicitly.
Where the arithmetic stops
Some chains cannot be resolved into a single ratio, and a calculator that pretends otherwise is inventing numbers:
- Fluids. Oil processing yields several products from one recipe. Attributing a share of the cost to just one of them requires an assumption, so we stop and report the fluid as an input instead.
- Alternate routes. Several items can be made more than one way — casting on Vulcanus, recycling scrap on Fulgora. We follow the standard Nauvis recipe and say so, rather than silently picking the cheaper path.
- Variable yields. Where a recipe states a range rather than a fixed amount, there is no single ratio to report.
A complete hand calculation: ten advanced circuits per second
The three-line formula is simple to state. Working through a full chain by hand shows where the repeated steps go and how the numbers connect. The target is ten advanced circuits per second, built in assembling machine 3s.
Step 1: the top level
An advanced circuit takes six seconds to craft and yields one. An assembling machine 3 runs at crafting speed 1.25, so each craft occupies a machine for 6 divided by 1.25 = 4.8 seconds. Ten crafts per second times 4.8 seconds per craft gives 48 assembling machines. Those 48 machines consume, per second: twenty electronic circuits, twenty plastic bars, and forty copper cable (two cable per circuit, ten circuits per second).
Step 2: electronic circuits
Electronic circuits use the default craft time of 0.5 seconds and yield one. In an assembling machine 3, each craft takes 0.5 divided by 1.25 = 0.4 seconds. Sustaining twenty circuits per second needs 20 times 0.4 = 8 assembling machines. Each circuit consumes one iron plate and three copper cable, so those eight machines need twenty iron plates and sixty copper cable per second. Combined with the forty cable the top level already needs, total cable demand is 100 per second.
Step 3: plastic bars
Plastic bars craft in one second in a chemical plant at crafting speed 1, yielding two bars per craft. Twenty bars per second requires 10 crafts per second, which is 10 chemical plants. Each craft consumes one coal and twenty petroleum gas, so the plants need 10 coal and 200 petroleum gas per second.
Step 4: copper cable
Copper cable also uses the default 0.5 second craft time and yields two cable per craft. One hundred cable per second requires 50 crafts per second, each taking 0.4 machine-seconds, giving 20 assembling machines. Cable consumes one copper plate per craft, so those 20 machines need 50 copper plates per second.
Step 5: smelting
Iron plates take 3.2 seconds in an electric furnace at speed 2, so each plate takes 1.6 furnace-seconds. The 20 iron plates per second for circuits need 32 furnaces. Copper plates also take 3.2 seconds at speed 2, and the 50 copper plates need 80 furnaces. Each plate consumes one ore, so the whole block draws 20 iron ore and 50 copper ore per second from the mines.
What the full chain looks like
| Stage | Rate / s | Machine | Machines | Inputs |
|---|---|---|---|---|
| Advanced circuit | 10 | ASM 3 | 48 | 20 circuits, 20 plastic, 40 cable |
| Electronic circuit | 20 | ASM 3 | 8 | 20 iron plates, 60 cable |
| Plastic bar | 20 | Chemical plant | 10 | 10 coal, 200 petroleum gas |
| Copper cable (total) | 100 | ASM 3 | 20 | 50 copper plates |
| Iron plate | 20 | Electric furnace | 32 | 20 iron ore |
| Copper plate | 50 | Electric furnace | 80 | 50 copper ore |
Every row is the same calculation: target rate divided by yield gives crafts per second; craft time divided by machine speed gives machine-seconds per craft; multiply for machine count. The only thing that changes between rows is which numbers go in. A calculator does this recursively until it reaches raw ore or a fluid it cannot attribute, which is exactly what the hand calculation does one row at a time.
Which recipes use the default 0.5 seconds
Out of 324 craftable recipes in the dataset, 270 state an explicit craft time and 54 omit the field. The engine assigns a default of 0.5 seconds to any recipe without a declared time. The omitted recipes are not random: they are overwhelmingly the simplest base-game items — iron gear wheels, copper cable, electronic circuits, transport belts, inserters, wooden chests, and the early smelting entities like stone furnaces and boilers.
The pattern makes sense historically. These recipes existed in the game's earliest versions and inherited a hardcoded 0.5 second timer before explicit energy_required fields were standardised. Later recipes — anything from the Space Age expansion, most intermediate products, anything with a fluid ingredient — declare their craft times explicitly.
The practical point is that a calculation using 0.5 seconds for a gear wheel is correct; the game does craft gears in half a second. But the number is an engine convention, not a value the recipe prototype declares. If a mod changed the default craft time (which mods can do), every one of those 54 recipes would shift at once without any individual recipe being edited. This page and the calculator use 0.5 seconds for them because that is what the running game uses, but the distinction matters when reasoning about why a recipe "has no craft time" in the data.
Checking whether the belts can carry it
A machine count is necessary but not sufficient. The belts and inserters between stages must also carry the flow, and a correct ratio that saturates a yellow belt is a correct ratio that stalls. The check is a separate division: items per second divided by belt throughput.
| Flow | Rate / s | Yellow belts | Red belts | Blue belts | Turbo belts |
|---|---|---|---|---|---|
| Copper cable (total) | 100 | 6.7 | 3.4 | 2.3 | 1.7 |
| Iron plate | 20 | 1.4 | 0.7 | 0.5 | 0.4 |
| Petroleum gas | 200 | Fluid — carried by pipes, not belts | |||
The cable line is the one to watch. One hundred cable per second needs seven yellow belts or two turbo belts. A bus that allocates one yellow belt to cable will not feed 48 advanced circuit machines. This is why production planners that report only machine counts can mislead: the arithmetic is right but the logistics cannot carry the result.
Inserters impose their own constraint. A standard inserter moving items from a belt to a machine has a swing time that limits how many items per second it can transfer. Machines that consume ingredients faster than a single inserter can supply them need multiple inserters or faster inserter tiers. The dataset includes inserter rotation speeds, but the throughput calculation depends on what the inserter is picking up and where it is putting it down, which is layout-specific. As with belts, the ratio is correct only if the items actually arrive.
Why the machine matters as much as the recipe
The same recipe in different machines produces different machine counts because crafting speed is a machine property, not a recipe property. An assembling machine 2 runs at speed 0.75; an assembling machine 3 runs at 1.25. For advanced circuits at 10 per second, that is the difference between 80 machines on ASM 2 and 48 on ASM 3.
| Machine | Crafting speed | Module slots | Power | Machines for 10 adv circuits |
|---|---|---|---|---|
| Assembling machine 1 | 0.5 | 0 | 75 kW | 120 |
| Assembling machine 2 | 0.75 | 2 | 150 kW | 80 |
| Assembling machine 3 | 1.25 | 4 | 375 kW | 48 |
The trade-off is not just footprint. ASM 3s draw 375 kilowatts each against 150 for ASM 2s, so 48 ASM 3s use 18 megawatts while 80 ASM 2s use 12 megawatts. The faster machine uses more power per machine but fewer machines, and the total power comparison depends on the recipe. Module slots compound the difference: four slots in an ASM 3 can carry speed or productivity modules that no ASM 2 can match with only two.
Smelting follows the same pattern. A stone furnace runs at speed 1, a steel furnace at 2, an electric furnace at 2. The steel and electric furnaces produce at the same rate, but the electric furnace accepts modules and the steel furnace does not. For unmodded smelting the machine counts are identical; once modules enter the plan they diverge. The solver picks the fastest machine that can run the recipe, which is why the chain above uses ASM 3 and electric furnaces rather than their slower equivalents.
A three-layer deep example: processing unit
Advanced circuit is a two-layer chain (circuit plus its immediate inputs). Processing unit goes deeper, and following it through shows how the recursion handles ingredients that have their own sub-ingredients.
One processing unit per second in an ASM 3 requires 8 ASM 3s at the top level (the recipe takes ten seconds at speed 1.25). Each processing unit consumes 20 electronic circuits, 2 advanced circuits and 5 sulphuric acid. Those become the target rates for the next layers: 20 circuits per second, 2 advanced circuits per second.
The electronic circuits need 8 ASM 3s, 32 electric furnaces for iron plates, 12 ASM 3s for copper cable (60 cable from the circuits plus the cable the advanced circuit stage needs), and 48 electric furnaces for copper plates. The advanced circuits need 9.6 ASM 3s, which in turn need electronic circuits, plastic bars and copper cable of their own — adding another 1.6 ASM 3s for circuits, 2 chemical plants for plastic, 2.4 ASM 3s for cable, and 9.6 furnaces for copper plates.
The totals at the leaves are 24 iron ore, 40 copper ore, 40 petroleum gas, 2 coal and 5 sulphuric acid per second. Notice that copper cable appears three times in the stage list (from circuits, from advanced circuits directly, and from the circuits that advanced circuits consume) but the solver sums them into one cable demand. Doing this by hand means carefully adding the duplicate stages; a calculator does it automatically, which is the main reason to use one past two layers.
Applies when…
- Machines are not starved of inputs or backed up on outputs; a ratio describes steady state, not startup.
- Belt and inserter throughput can carry the flow. A correct ratio still fails if the belt saturates.
- Recipes are the standard Nauvis ones for the stated game version.
- Fractional machine counts are exact. Rounding up leaves idle capacity; rounding down misses the target.