Furnace 20

Lore & Background

In the sprawling industrial sprawl that the player builds atop an alien world, the furnace is the beating heart of every production line. It is the first machine that transforms raw geology into something usable: iron ore becomes iron plates, copper ore becomes copper plates, stone becomes concrete. The progression from a rough-hewn Stone Furnace to a gleaming Electric Furnace mirrors the broader arc of the game—moving from hand-picked rocks and basic automation to a fully electrified, high-throughput industrial complex. The Steel Furnace, unlocked with the Steel Furnace technology, represents the first meaningful leap: it smelts faster and can process more items simultaneously. The Electric Furnace, requiring the Electric Furnace technology, is the final tier in the base game and offers yet another speed increase. For the player, upgrading furnaces is often one of the most satisfying early-to-mid-game milestones, as the bottleneck of smelting finally yields to the rest of the factory's ambitions. Because no 'Furnace 20' exists, any fan-fiction, speedrun commentary, or community meme referencing that name is purely imaginative. The real story of Factorio's furnaces is one of steady, honest escalation: you start with a chunk of stone and a bag of coal, and you end with a wall of humming electric boxes feeding a thousand belts.

In Their Own Story

The first furnace was ugly. A rectangle of grey stone, barely larger than a crate, with a single slot where you shoved iron ore and a second where you shoved coal. It clanked. It hissed. It spat out one iron plate every few seconds, and you stood there watching it like a child watching a toaster pop a single slice of bread. By the time you'd built the second one, you were no longer watching. You were laying belts. By the Steel Furnace, you were laying *walls* of furnaces, each one a small orange glow in the dusk, and the coal conveyor feeding them looked like a river of black water. You stopped counting plates. You started counting *per minute*. The Electric Furnace came on a Tuesday. You remember because it was raining, and the little blue sparks it threw off when you placed it looked almost like lightning trapped in a box. You lined up forty of them in a row, fed them from a single belt, and the smelting bottleneck simply… vanished. Like it had never been there. Like the stone furnace you'd coddled in the first hour of the game was a different species of machine entirely. It wasn't. It was the same idea, just faster. That's the whole game, really. The same idea, just faster.

Reader's Guide

Furnace progression in Factorio follows a clean three-step technology chain. The Stone Furnace is available from the start—no research required—making it the default smelting unit for every new save. The Steel Furnace is unlocked by researching the 'Steel Furnace' technology, which requires Steel as a prerequisite material and sits in the early-to-mid tech tree. The Electric Furnace is unlocked by the 'Electric Furnace' technology, which requires the Steel Furnace tech as a prerequisite and typically appears in the mid-game once the player has access to electricity and more advanced components. Each tier increases smelting speed: the Stone Furnace is the slowest, the Steel Furnace is noticeably faster, and the Electric Furnace is the fastest in the base game. All three accept the same fuel types (coal, wood, or solid fuel) and the same input/output items; the difference is purely throughput. In large factories, furnace throughput is often the first bottleneck players hit, so upgrading from Stone to Steel is a common early optimization, and upgrading to Electric is a standard mid-game priority. There is no 'Furnace 20' or any numbered furnace tier in the base game. Community mods may add additional furnace variants, but these are not part of the canonical tech tree. When sharing blueprints, furnace type is baked into the blueprint data, so a blueprint containing Stone Furnaces will place Stone Furnaces regardless of the player's current tech level—though the player must have the corresponding technology to *use* them effectively.

Did You Know?

• The Stone Furnace is the only furnace available without any technology research, making it the first machine most players ever place in a new game.
• All three furnace tiers in the base game accept the same fuel options (wood, coal, solid fuel); the upgrade is purely a speed increase, not a fuel-type change.
• Furnace throughput is one of the most commonly cited early-game bottlenecks in Factorio, and upgrading from Stone to Steel Furnaces is a standard first optimization for players struggling with iron and copper plate produ
• The Electric Furnace produces a small visual effect of blue electrical sparks, distinguishing it visually from the orange-glowing Stone and Steel Furnaces.