Smelting is the quiet backbone of every Factorio base. Before you ever touch trains, robots, or rockets, you’re feeding iron ore and copper ore into furnaces and turning them into the plates that build literally everything else. Get your smelting ratios right early and the rest of your factory scales cleanly; get them wrong and you’ll be fighting starved assemblers and half-empty belts for the rest of the playthrough. This guide breaks down all three furnace tiers, the belt throughput math that decides how many furnaces you actually need, and the module setups that push electric smelting to its limits.
Everything here is current for Factorio 2.0 and the Space Age expansion, both of which launched on October 21, 2024. The 2.0 update is the current stable line as of 2026, and where a mechanic differs from the old 1.1 era, we flag it clearly so you don’t follow outdated advice.
The three furnace tiers at a glance
Factorio gives you exactly three furnace types, and each one is a clear upgrade over the last. The progression is intuitive: stone furnaces get you off the ground, steel furnaces double your output for the same fuel, and electric furnaces unlock modules and beacons so your endgame smelting can be supercharged. Here’s how they compare at normal quality:
| Furnace | Crafting speed | Power / fuel | Module slots | Pollution |
|---|---|---|---|---|
| Stone Furnace | 1 | 90 kW, burner (wood/coal/solid/rocket/nuclear fuel) | 0 | — |
| Steel Furnace | 2 | 90 kW, burner (same fuels) | 0 | — |
| Electric Furnace | 2 | 180 kW active, 6 kW idle drain (electric) | 2 | 1/m |
The single most important takeaway from that table: the steel furnace runs at twice the speed of a stone furnace while drawing the exact same 90 kW of fuel. That makes it twice as fuel-efficient per plate produced. It’s one of the best early-game upgrades in the entire game, and it’s cheap — each steel furnace is crafted from just 6 steel plates + 10 stone bricks with a 3-second craft time. The moment you have steel processing online, you should be planning your switch.
Tier 1: Stone furnaces
The stone furnace is your starter. It has a crafting speed of 1, runs as a burner on any solid fuel (wood, coal, solid fuel, rocket fuel, or nuclear fuel), and consumes 90 kW. It has zero module slots, so what you see is what you get. You’ll hand-feed these with wood early on, then automate coal delivery as soon as you can. Stone furnaces are perfectly fine for the first hour or two of a game, but because they’re half as efficient as steel for the same fuel draw, they’re a stepping stone, not a destination.
Tier 2: Steel furnaces
Steel furnaces are the workhorse of the mid-game. Same 90 kW fuel draw, but double the crafting speed (2 vs 1). They still have no module slots, so you can’t boost them with speed or productivity modules — but they don’t need power infrastructure either, which makes them ideal before your electric grid is robust. A common strategy is to build out a steel smelting array early and run it for the entire mid-game, only switching to electric once you have a stable power network and a module supply chain.
Tier 3: Electric furnaces
The electric furnace matches the steel furnace’s crafting speed of 2, but instead of burning fuel it draws 180 kW of power while active (and a small 6 kW idle drain when there’s nothing to smelt). The killer feature is the 2 module slots — electric furnaces are the only tier that accepts modules at all. That means productivity, speed, and efficiency modules, plus beacon coverage, are all exclusive to electric smelting. It does produce a small amount of pollution (1/m), but the trade-off is that with the right modules and beacons, an electric furnace array dwarfs anything you could build with burners.
Belt throughput math: how many furnaces do you actually need?
This is the part most guides hand-wave, and it’s the part that actually matters when you’re laying out a base. Your furnace count should be driven by one question: how many plates per second do I want flowing out, and how fast can each furnace produce a plate?
Start with belt throughput. Factorio’s three transport belts move items at fixed rates:
- Yellow belt (Transport belt): 15 items/s
- Red belt (Fast transport belt): 30 items/s
- Blue belt (Express transport belt): 45 items/s
Now the production side. Smelting iron or copper ore into a plate has a base craft time of 3.2 seconds. A steel or electric furnace runs at crafting speed 2, which effectively halves that — so each one finishes roughly one plate every ~1.6 seconds. Divide a belt’s throughput by that output rate and you get your furnace count.
Furnace output (steel/electric) = 1 plate / 1.6 s ≈ 0.625 plates/s
Yellow belt (15/s) ÷ 0.625 ≈ 24 steel/electric furnaces
Red belt (30/s) ÷ 0.625 ≈ 48 steel/electric furnaces
Blue belt (45/s) ÷ 0.625 ≈ 72 steel/electric furnacesSo the headline number to memorize: roughly 24 steel or electric furnaces saturate one full yellow belt of plates. To fully fill a blue belt you’d need roughly double the steel furnace count of a yellow-belt line, scaling up the same way.
Because stone furnaces run at half the speed (crafting speed 1), they produce a plate at roughly half the rate, so the classic mental model is about 48 stone furnaces to saturate one full yellow belt — twice the count of steel. These “furnaces per belt” figures are derived from the craft-speed and throughput math above rather than quoted from a single source, so treat them as solid planning guidance rather than gospel; the underlying speeds (stone 1, steel/electric 2) are the verified numbers to anchor on.
| Output target | Stone furnaces (speed 1) | Steel / Electric furnaces (speed 2) |
|---|---|---|
| Full yellow belt (15/s) | ~48 | ~24 |
| Full red belt (30/s) | ~96 | ~48 |
| Full blue belt (45/s) | ~144 | ~72 |
A practical tip: build your smelting array as a “block” of furnaces aligned along an input belt of ore and an output belt of plates, sized to exactly fill one belt tier. When you outgrow it, you copy-paste the whole block rather than re-doing your ratios. A yellow-belt block of 24 furnaces is the natural starting unit; upgrade the belts to red and add a second block, and you’ve doubled output without re-thinking the layout.
Modules and beacons: the electric-only endgame
Here’s where electric furnaces pull decisively ahead. Their 2 module slots accept three families of modules, and this is the only furnace tier that can use them:
- Productivity modules — yield extra plates per ore consumed, at the cost of increased pollution and energy use. The headline win: more plates from the same ore mine, which effectively stretches your ore patches further.
- Speed modules — make the furnace craft faster, raising plates-per-second per furnace (and letting fewer furnaces fill a belt).
- Efficiency modules — reduce energy consumption and pollution, useful if your power grid or biter aggression is a concern.
The standard endgame pattern is to load productivity modules into the furnace’s two slots (to squeeze more plates per ore), then surround the array with beacons projecting speed modules to claw back the speed penalty productivity imposes — and then some. Beacons only affect machines with module slots, so once again, this entire optimization tier is locked to electric furnaces. Stone and steel furnaces simply cannot participate.
One 2.0/Space Age note: the quality system (introduced in 2.0, did not exist in 1.1) lets you build higher-tier furnaces — uncommon through legendary — that scale crafting speed and other stats upward. The base speeds in this guide are quoted at normal quality, so if you’re running higher-quality electric furnaces, your real-world furnace-per-belt counts will be lower than the figures above. Recompute from your machine’s actual crafting speed if you go down the quality route.
A practical smelting progression
Pulling it together, here’s how a smelting setup typically evolves across a playthrough:
- Early game — stone furnaces, hand-fed. Drop a handful of stone furnaces, feed them wood or coal, and smelt enough iron and copper to bootstrap your first assemblers. Don’t over-invest here.
- Mid game — steel furnace array on yellow belts. As soon as steel is automated, build a ~24-furnace block per yellow belt of each plate type. Same fuel, double the throughput. Automate coal delivery to the array.
- Late game — electric furnaces with modules. Once your power grid is stable, switch to electric furnaces, slot in productivity modules, and ring the array with speed beacons. Upgrade belts to red or blue and scale the block count to match.
Smelting is also one of the steadier loads on a multiplayer server — furnace arrays run continuously and benefit from consistent UPS, which is exactly what dedicated hosting delivers. If you’re running a persistent base with friends, you can spin up a dedicated Factorio server so your smelting columns keep humming even when nobody’s online to babysit the coal supply. For the nuts and bolts of getting your world configured, our Factorio server setup documentation walks through the whole process.
Powering your smelting setup
Steel furnaces sidestep the power question entirely by burning fuel, but the moment you go electric, a 24-furnace block pulls 24 × 180 kW ≈ 4.3 MW under full load — and that’s before beacons and the rest of your factory. Your power infrastructure has to keep pace or you’ll brownout, where the whole grid slows proportionally when supply drops below demand.
If you’re on early steam power, note the big 2.0 change: the offshore-pump ratio was reworked. In 1.1 the classic ratio was 1 offshore pump : 20 boilers : 40 steam engines (about 40 MW). In 2.0, the offshore pump now outputs 1200 water/s, and with the 10:1 water-to-steam ratio that makes the optimal layout 1 offshore pump : 200 boilers : 400 steam engines (about 360 MW). The boiler-to-engine ratio of 1:2 is unchanged. Any older guide citing 1:20:40 is 1.1-only — don’t copy it into a 2.0 base. Our comprehensive power management guide covers steam, solar, and accumulator ratios in detail.
For solar, the famous ratio still holds: roughly 25 solar panels : 21 accumulators (about 0.84 accumulators per panel) for fully sustained day-and-night power on Nauvis. Just remember that figure is Nauvis-specific — on Space Age planets like Vulcanus or Fulgora, day length and solar multipliers differ, so the 25:21 ratio doesn’t transfer.
Fitting smelting into the bigger factory
A well-tuned smelting array is the start of a much larger automation chain. The plates feed your assemblers, but the supporting cast around it deserves attention too. Once your base sprawls, construction and logistic robots take over the tedious work of restocking modules, hauling plates, and rebuilding any furnaces that get chewed up by an attack. And speaking of attacks — electric furnaces produce pollution (1/m each), which contributes to biter evolution and aggression. A large electric smelting block is a meaningful pollution source, so if you’re seeing more frequent raids, your smelting array is part of the reason. Our guide to dealing with biters covers walls, turrets, and the evolution drivers (time, pollution, and spawner kills) you’ll want to manage.
As your furnace blocks multiply, the bottleneck shifts from smelting to moving raw ore and finished plates across the map. That’s when most players graduate from belts to a rail network, shipping ore in from distant mines and plates back to the mall. If you’re at that stage, dialing in your signals matters — see our train systems guide for the “chain in, rail out” rule that keeps your ore deliveries flowing without deadlocks.
Frequently asked questions
How many furnaces does it take to fill a yellow belt?
About 24 steel or electric furnaces (crafting speed 2) saturate one full yellow belt (15 items/s), since each produces roughly one plate every 1.6 seconds. With stone furnaces (crafting speed 1), you need roughly double — about 48 — to fill the same belt.
Are steel furnaces really better than stone?
Yes, decisively. A steel furnace runs at crafting speed 2 versus the stone furnace’s 1, while drawing the exact same 90 kW of fuel. That makes it twice as fast and twice as fuel-efficient per plate. Each steel furnace costs only 6 steel plates and 10 stone bricks, so the upgrade pays for itself almost immediately.
Can I put modules in stone or steel furnaces?
No. Only electric furnaces have module slots (2 of them). Stone and steel furnaces have zero slots, so productivity, speed, and efficiency modules — as well as beacons — only work on electric furnaces. This is the main reason to transition to electric smelting late-game.
How much power does an electric furnace use?
An electric furnace draws 180 kW while actively smelting and a small 6 kW idle drain when it has nothing to process. That’s double the power figure of a burner furnace’s 90 kW fuel draw, but it trades fuel logistics for grid power and unlocks module and beacon support.
Did smelting change in Factorio 2.0?
The core furnace stats — speeds of 1, 1.6 (no, 2), and power draws — carry forward from 1.1. The main 2.0 addition affecting smelting is the quality system, which lets you build higher-quality furnaces (uncommon through legendary) with scaled crafting speeds. All base stats in this guide are quoted at normal quality. The bigger 2.0 ratio change to watch out for is on the power side: the steam offshore-pump ratio shifted from 1:20:40 to 1:200:400.
What’s the best smelting setup for a server?
For a persistent multiplayer base, build modular furnace blocks sized to one belt tier (24 furnaces per yellow belt, scaling up with red and blue belts), and transition to electric furnaces with productivity modules and speed beacons once your power grid is stable. Run it on a hosted Factorio server so the array keeps producing around the clock, and use logistic robots to auto-restock modules and repair furnaces after biter raids.
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