The Factorio ratios that matter most for a first factory: one yellow belt carries 15 items a second, so it needs 30 electric mining drills (0.5 ore/s each) and 48 stone furnaces (0.3125 plates/s each) to fill. One boiler feeds two steam engines, and one offshore pump supports 200 boilers and 400 engines. A 60-packs-a-minute red and green science build runs on about 21 assembling machine 2s. The numbers below come from the official Factorio Wiki and the game’s own machine stats, checked on November 9, 2026 against version 2.1.24, the current stable build on factorio.com.
Table of Contents
Quick answer: Factorio ratios to memorise
- Yellow belt: 15 items/s total, 7.5 per lane.
- Mining: electric mining drill = 0.5 ore/s. 30 drills fill one yellow belt.
- Smelting: stone furnace = 0.3125 plates/s; steel or electric furnace = 0.625/s. 5 drills feed 8 stone furnaces or 4 steel furnaces.
- Power: 1 boiler : 2 steam engines (1.8 MW burned, 1.8 MW made). 1 offshore pump : 200 boilers : 400 engines.
- Circuits: 3 copper-cable assemblers for every 2 circuit assemblers.
- Science: 1 red pack needs 1 copper plate and 1 gear (2 iron). 1 green pack needs 1.5 copper and 5.5 iron in total.
- Labs: packs per second = labs / research cycle time (before bonuses).
Factorio is Wube Software’s factory-building game, $35 on Steam. Everything here is for the base game on Nauvis with base-quality machines and no modules or beacons, so the figures are the plain starting point you scale from.
Mining and smelting ratios: drills, furnaces and belts
Start with the plate supply, because every later ratio is a share of it. The Electric mining drill page gives 0.5 ore per second for iron, copper, coal and stone, and the furnace output table gives the smelting speeds. The Transport belt page lists the yellow belt at 15 items per second.
| Machine | Rate | Needed to fill one yellow belt (15/s) |
|---|---|---|
| Electric mining drill | 0.5 ore/s | 30 drills |
| Stone furnace | 0.3125 plates/s | 48 furnaces |
| Steel furnace | 0.625 plates/s | 24 furnaces |
| Electric furnace | 0.625 plates/s | 24 furnaces |
Two ratios fall out of that table. Five drills make 2.5 ore a second, which is exactly what 8 stone furnaces (8 x 0.3125) or 4 steel furnaces (4 x 0.625) smelt. So a column of 8 stone furnaces wants 5 drills behind it, and upgrading to steel furnaces halves the furnace count for the same ore.
Stone and steel furnaces both burn about 0.0225 coal a second while working, per the wiki’s table, so 48 stone furnaces use roughly 1.1 coal/s and 24 steel furnaces about 0.5 coal/s. That is why steel furnaces are the cheaper upgrade for fuel. Electric furnaces need no coal but draw 180 kW each.
A yellow belt moves 15 items a second, so every ratio here is a share of that. Image: Wube Software
Assembler ratios: how many machines per recipe
Every assembler follows one formula: items per second = crafting speed x items per craft / recipe time. Crafting speeds are 0.5 for the assembling machine 1, 0.75 for the assembling machine 2 and 1.25 for the assembling machine 3. These are the outputs per machine for the recipes you build most:
| Recipe | Recipe time | AM1 | AM2 | AM3 |
|---|---|---|---|---|
| Iron gear wheel (2 iron plates) | 0.5 s | 1/s | 1.5/s | 2.5/s |
| Copper cable (1 copper makes 2) | 0.5 s | 2/s | 3/s | 5/s |
| Electronic circuit | 0.5 s | 1/s | 1.5/s | 2.5/s |
| Inserter | 0.5 s | 1/s | 1.5/s | 2.5/s |
| Transport belt (2 per craft) | 0.5 s | 2/s | 3/s | 5/s |
| Automation (red) science pack | 5 s | 0.1/s | 0.15/s | 0.25/s |
| Logistic (green) science pack | 6 s | 0.083/s | 0.125/s | 0.208/s |
The classic circuit ratio comes straight from this. A circuit needs 3 copper cables and 1 iron plate, and cable and circuit recipes both take 0.5 s, but a cable craft makes 2. One circuit assembler eats 3 cables a craft, one cable assembler makes 2, so the match is 3 cable assemblers : 2 circuit assemblers at any machine tier. Build the cable assemblers right next to the circuit ones and feed them directly, because the wiki’s main bus tutorial points out that cable takes more belt space than the copper plate it is made from.
Red and green science ratios: how many assemblers for 60 packs a minute
Science is where ratios stop being trivia, because it sets how fast you can research. The automation science pack recipe is 1 copper plate plus 1 gear wheel (2 iron) in 5 seconds. The logistic science pack is 1 inserter plus 1 transport belt in 6 seconds. Counting every sub-ingredient, a red pack costs 1 copper and 2 iron, and a green pack costs 1.5 copper and 5.5 iron.
The table is sized for 1 pack per second of each colour, which is 60 per minute. Scale it down linearly for a smaller start (30 per minute is half of everything).
| Stage (for 1 pack/s) | AM1 | AM2 | AM3 |
|---|---|---|---|
| Red science assemblers | 10 | 7 (6.7 exact) | 4 |
| Green science assemblers | 12 | 8 | 5 (4.8 exact) |
| Gear wheels for red (1/s) | 1 | 1 | 1 |
| Gear wheels for green (1.5/s: inserters + belts) | 2 | 1 | 1 |
| Inserter assemblers (1/s) | 1 | 1 | 1 |
| Belt assemblers (1/s) | 1 | 1 | 1 |
| Circuit assemblers (1/s) | 1 | 1 | 1 |
| Copper-cable assemblers (3/s) | 2 (1.5 exact) | 1 | 1 |
With assembling machine 2s that is 7 + 8 science machines plus 6 helper machines (two of them gear assemblers shared by both packs), so roughly 21 AM2 for 60 SPM of red and green. The wiki’s own ratio boxes use assembling machine 3s and show the same logic: 10 AM3 make 150 red packs a minute and 24 AM3 make 300 green packs a minute.
Raw plates for that 60 SPM build: 2.5 copper and 7.5 iron per second in total (1 + 1.5 copper, 2 + 5.5 iron). In machines that is 15 iron drills and 5 copper drills, 24 stone furnaces on iron and 8 on copper, and the iron fits on half of one yellow belt.
Science assemblers and labs: for a 30-second technology, 30 labs use 1 pack of each colour a second. Image: Wube Software
How many labs do you need?
The Lab page gives the formula: each lab uses one pack of each required colour per research cycle, so with no research bonuses the packs consumed per second equal labs divided by the technology’s cycle time. A technology with a 30 second cycle therefore burns 1 pack a second of each colour with 30 labs, which is exactly the 60 SPM above. For a 15 second technology the same 60 SPM only feeds 15 labs. Each lab draws 60 kW. Research speed bonuses and speed modules divide the cycle time, so they cut the lab count in the same proportion.
Power ratios: boilers, steam engines and offshore pumps
Steam power is the part new players overbuild. A boiler burns 1.8 MW of fuel, drinks 6 water a second and makes 60 steam a second. A steam engine turns 30 steam a second into 900 kW. So the ratio is 1 boiler : 2 steam engines. The offshore pump makes 1,200 water a second, which covers 200 boilers and 400 engines. The wiki’s power production page states the same 1 : 200 : 400 figure.
| Block | Boilers | Engines | Output | Coal at full load |
|---|---|---|---|---|
| Starter | 1 | 2 | 1.8 MW | 0.45/s |
| Small base | 10 | 20 | 18 MW | 4.5/s |
| Max from one pump | 200 | 400 | 360 MW | 90/s |
One boiler needs roughly 0.45 coal a second, and a full yellow belt of coal (15/s) can feed about 33 boilers, or 60 MW, according to the wiki. In practice a single pump is never the limit in a first factory. Coal supply and inserter speed run out first.
How many machines does one steam engine run?
One engine (900 kW) covers about 10 electric mining drills (90 kW each), 12 assembling machine 1s (75 kW), 6 assembling machine 2s (150 kW), 15 labs (60 kW) or 5 electric furnaces (180 kW), all at full load. For our 60 SPM example that is about 21 AM2 (3.15 MW), 20 drills (1.8 MW) and 30 labs on a 30 second technology (1.8 MW): roughly 6.75 MW, or 8 engines and 4 boilers, before inserters and idle drain. That is our own arithmetic from the machine figures above, not a wiki-listed build.
Solar panel and accumulator ratio
A solar panel peaks at 60 kW but averages 42 kW over a day. The wiki’s power production page gives the optimal ratio as 0.84 accumulators per panel (21 : 25), or about 23.8 panels per megawatt including the panels that charge the accumulators. Its rough rule is 20 accumulators and 24 panels per megawatt. Replacing one steam engine (0.9 MW) day and night would take about 21 panels and 18 accumulators.
Zoomed out, a base is a set of ratios joined by belts and rails. Image: Wube Software
Main bus ratios: how many belts of each plate
If you build a main bus, the wiki’s tutorial suggests several iron belts in a multiple of four, since that is how far one underground belt reaches, and says you need about as much copper overall as iron (early science is iron-heavy, so that fits later builds better). It advises leaving two free tiles per group of four belts so underground belts can surface and cross. Using the science numbers above, a bus that feeds 60 SPM of red and green needs half a belt of iron and a sixth of a belt of copper, so one iron belt and one copper belt leave plenty of room to grow.
Common Factorio ratio mistakes
- Counting belts, not lanes. A single lane carries 7.5 items/s, so a belt with only one lane in use tops out at half the 15/s figure used throughout this page.
- Underbuilding gears. Gears feed red science, inserters, belts and many buildings. One AM1 makes only 1 a second, so gear assemblers are the first bottleneck on a small base.
- Mixing furnace tiers. 5 drills per 8 stone furnaces drops to 5 drills per 4 steel furnaces. Keep the drill count when you upgrade, not the furnace count.
- Trusting the exact count. 6.7 AM2 for red science means 7 machines running at 95 percent. Round up, never down, and let the belt back up.
Related guides on our site: our Satisfactory beginner tips cover similar production-line thinking in 3D, the Anno 117 production chains and ratios post is the city-builder version, and the Oxygen Not Included tips do the same numbers-first approach for a colony sim.
FAQ
How many furnaces per belt in Factorio?
48 stone furnaces or 24 steel or electric furnaces fill one yellow belt of 15 plates a second. You also need 30 electric mining drills on the ore side.
How many boilers per offshore pump?
One offshore pump (1,200 water/s) supports 200 boilers, which in turn feed 400 steam engines. In a normal base you will never come close to that limit.
How many steam engines per boiler?
Two. A boiler makes 60 steam a second and each engine uses 30 of it, so 1 boiler runs 2 engines for 1.8 MW.
How many assemblers do I need for red science?
For 1 pack a second, 10 assembling machine 1s, about 7 assembling machine 2s or 4 assembling machine 3s, plus one gear assembler.
What is the Factorio circuit ratio?
3 copper-cable assemblers to 2 electronic-circuit assemblers.
Sources: Factorio Wiki: Electric mining drill, Stone furnace, Transport belt, Power production, Lab, Main bus; factorio.com latest releases (stable 2.1.24); Steam. Checked November 9, 2026.
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Featured image: Wube Software
