Furnace 25

Lore & Background

In the sprawling, rust-streaked world of Factorio, the first furnace a player lights is almost always a Stone Furnace, its little flame flickering to life as iron ore clatters into the input slot. The game's early chapters revolve around this humble building: feed it ore, wait, collect plates, repeat. But as the player's factory sprawls across the alien grassland, a single furnace becomes a bottleneck, and the urge to systematize smelting takes over. "Furnace 25" emerged in the community as a practical, repeatable answer to that bottleneck. Rather than scattering furnaces haphazardly around a base, a player arranges exactly twenty-five of them in a tight grid or row, pairs them with inserters and a small buffer of ore, and saves the whole arrangement as a blueprint. The number twenty-five is not sacred to the game's code; it is simply a size that feels right for an early-to-mid game smelting station—large enough to keep up with a growing circuit demand, small enough to fit beside a handful of assemblers without eating the entire map. Because blueprints in Factorio are purely geometric templates, the same "Furnace 25" layout can be built with Stone Furnaces in the early game, then rebuilt with Steel Furnaces once the player has access to the Steel Processing technology, and eventually replaced entirely by an Electric Furnace bank. The blueprint name persists across these upgrades as a cultural shorthand among players: "I just dropped a Furnace 25 next to the copper line." It is less a technology and more a habit, a shared vocabulary of factory-building that the game's open-ended design naturally encourages.

In Their Own Story

The dust had settled over the flat, grey-green plain, and the little red flame in the first Stone Furnace had burned for what felt like three in-game hours. Mara watched the iron plates tick up—twelve, thirteen, fourteen—and felt the familiar itch in her fingers. One furnace. One single, stubborn, beautiful furnace, and it was not enough. She pulled up the blueprint she'd saved that morning: a neat rectangle of twenty-five furnace slots, inserters already wired in, a small ore buffer on the south side. She pressed the build key, and the ground shuddered softly as the new furnaces materialized in a perfect grid, their little chimneys standing like a row of dark sentinels against the pale sky. She fed the first batch of iron ore into the northernmost slot, watched the flame catch, and felt the factory breathe. Somewhere to the east, a copper vein glistened under the low sun. She would get to that next. But for now, twenty-five furnaces hummed in unison, and the plates came like rain.

Reader's Guide

Furnace 25 is not a researchable technology; it is a community blueprint. In Factorio, any player can select a group of placed items (furnaces, inserters, belts, buffers), open the blueprint menu, and save that arrangement as a named blueprint. The blueprint can then be shared via a short code or pasted directly into another player's world. When another player builds it, the game places the items in the exact same relative positions, but the player chooses which furnace tier to use—Stone, Steel, or Electric—by having that tier selected in their build menu before placing the blueprint. The prerequisite chain for the furnace tiers it references is: Stone Furnace is available from the start (no prerequisite beyond basic crafting); Steel Furnace requires the Steel Processing technology, which in turn requires Steel and a Science Pack; Electric Furnace requires the Advanced Circuit technology, which needs Plastic Bars and a more advanced science setup. So a player can build a "Furnace 25" with Stone Furnaces immediately, then later rebuild the same footprint with Steel or Electric Furnaces as their tech tree advances. The blueprint interacts with the tech tree purely through the furnace tier the player selects at build time. The layout geometry itself has no tech dependency. Notable community designs in this vein include long single-row furnace lines paired with a single inserter per furnace, and compact 5×5 grids that minimize belt routing. Because the blueprint is just a spatial template, it composes cleanly with larger factory blueprints: a player can nest a Furnace 25 inside a broader smelting-farm blueprint without conflict.

Did You Know?

• In Factorio, a blueprint is purely a spatial template; it stores positions and item types but not the specific furnace tier, so the same blueprint can be built with Stone, Steel, or Electric Furnaces depending on what th
• The base game includes exactly three furnace tiers—Stone, Steel, and Electric—each roughly doubling the smelting speed of the previous one, making furnace upgrades one of the most impactful early-game throughput gains.
• Players can share blueprints via a short alphanumeric code, meaning a "Furnace 25" layout can be transmitted between players without any external mod or network connection.
• Because furnaces in Factorio are directional and their input/output slots face a fixed direction, a well-designed furnace blueprint like this one must account for inserter reach and belt routing, which is why the 25-unit