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"Factorio": How to Build a Furnace/Smelting Setup

KatherineOfSky has over 2,000 hours in Factorio and has published many video guides, Let's Plays, and tutorials for the game on YouTube.

Starting out in Factorio can be a boatload of information! Lots of numbers, rates and ratios bombard you with data! In this tutorial, we'll break those down to build efficient smelting columns that will last you until end-game.

Location, Location, Location!

When you are designing your columns, keep in mind where you want your main bus structure to be and the direction it will go. You'll want your smelting area to be at the beginning of the bus with space for expansion.

At the beginning of the game, you'll want at least one full belt of iron and one of copper, but you should leave space for at least four belts of each -- that means eight smelting columns total in the main base. Later on, you will probably want to move smelting to outposts, so no need to plan for more space than that.

Smelting columns require ore and coal to function, so keep that in mind when you are planning on where to put them. Initially, your iron supply for making belts is pretty limited, so placing the array close to those sources is desirable.

A good location is near the ores

A good location is near the ores


Let's talk about ratios for a moment. We want to make a full yellow belt of plates. A yellow belt moves 15 items per second. A Stone Furnace can make 0.3125 plates per second. Fifteen divided by 0.3125 is 48 -- thus we need 48 furnaces to make a full belt. Luckily the ratio of ore to plates is 1:1 for iron and copper, so we can plan around one belt in to one belt out.

Looking at the "Factorio Cheat Sheet" web site, we can see that there is a commonality in numbers of furnaces. Because red belts are twice as fast as yellow and steel furnaces are twice as fast as stone, with this array, we can use yellow belts and stone furnaces and upgrade to red belts and steel furnaces and not have to change anything about the design! This is very handy!


Building Step by Step

Over the years, I've created and seen so many different designs. My favorite, and probably the most efficient is one that I've adapted is from JDPlays. I modified the fuel delivery system a bit to fit with my playstyle.

This design uses two columns of furnaces: 24 on each side of a central output belt. Place the first row of smelters. Leave a 1 tile space, then place an output belt going in the direction of your planned main bus. Leave a 1 tile space and then place the second line of furnaces.


The feeding belts are going to go around the outside of the furnaces. Again, leave a 1 tile space between the furnaces and belt, and make sure it too is facing the same direction as the output belt.


Now we come to the sneaky and brilliant part of this design: the splitters that feed the belts. At the head of the array, leave 4 spaces between the furnaces and splitters. Place two splitters facing each other with a 1 tile gap between. Now place belts going toward the outside feeding belts of the array. Because of the propinquity (closeness) of the splitters, they only feed half of each belt, allowing us to have ore consistently on one side, and fuel on the other, a perfect split!

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Now, we'll put in the fuel delivery belt, which requires a split to the splitter, and undergroundies to go underneath the feeding belts on the sides of the array. The reason we put fuel on this belt instead of ore is that much less fuel is required for smelting. One yellow belt of coal can feed 666 furnaces! That's almost 14 arrays! However, a full belt of iron or copper is required on the other side.


Time to put in the inserters! They are super easy: place one going in and one out for each of the furnaces. Run up and down the array to place Small Power Poles automatically.


Ore & Coal

We're ready to go, but we still need one thing! Ore! To feed this array we'll need 30 Electric Miners. (When you upgrade to red belts, you'll need 60). Make sure you place the miners to fill both sides of the belt evenly. You can easily count miners by selecting them with a blueprint or deconstruction planner and just pressing Q to cancel after you see the number. Keep in mind that miners on the ends of the field will run out of ore faster than those in the middle of the field, so place extra miners on the belt.

Place down at least 30 miners to fill a yellow belt

Place down at least 30 miners to fill a yellow belt

If you want to be precise about coal, you'll need 2.2 coal miners per smelting array, but I usually spam it to a full belt once I am able to make enough miners.

Coal to power the furnaces

Coal to power the furnaces

Let's put Steel in that gap!

You've probably noticed that there is still one tile of extra space in the furnace array. That's so we have the ability to place down steel arrays and they'll be in perfect alignment.

The setup is very similar: this array will smelt ore into plates into steel. Steel takes 5 times the amount of time to smelt as iron plates, and requires 5 iron plates, so a direct feed array is perfect! Keep in mind that you will need 5 arrays like this one in order to produce a full belt!

The Steel column also needs to be 24 furnaces long

The Steel column also needs to be 24 furnaces long


Whenever you are ready to upgrade to steel furnaces, remember that they burn the same amount of fuel as stone ones, but produce at twice the speed, so you are essentially using only half the fuel. Thus, I like to upgrade to red belts as soon as possible. (Remember to add another 30 miners and a red belt from the ore patch to feed them!)

Note that you do NOT have to upgrade the output inserters

Note that you do NOT have to upgrade the output inserters

Blueprint Variations

In my blueprints cache I keep arrays for left feeding belts, right feeding belts, and also one for in and out on the same side. This can be useful for very pretty setups where ore comes in and the plates belt takes it's place on the way out.


Stone Bricks

When you are making Stone Bricks each requires 2 pieces of stone, so the smelting arrays should be half as long, but you'll need twice as many unless you feed from the side. That is: you need 2 full belts of stone to get one belt of Stone Bricks out.


Electric Furnaces?

In the old days of Factorio, people used to make arrays that could accommodate 3x3 Electric Furnaces. However, we know that electric furnaces are the same speed as Steel Furnaces and they are more energy efficient if you are using solid fuels like coal or solid fuel.

There are very few reasons to use electric:

  1. You are building in a location without fuel.
  2. You are moving toward an end-game moduled system using productivity modules with speed beacons.
  3. You are using solar power for your base. ("Free" power).

Otherwise, stick with Steel furnaces! There is plenty of coal around, and they are super efficient!

Old-style setup

Old-style setup

Moduled end-game setup

Moduled end-game setup

© 2020 KatherineOfSky


Brovahkiin on September 05, 2020:

huge shout out to you for actually writing all these detailed tutorials alongside the video!

video might be prefered by many but skipping back and forth to when exactly the crucial information is shown can be tedious...

you should definetly highlight your link a little more so more people see this!

now I'm a bit torn as to when to start using electric with speed modules, I really hate to replace existing arrays

I guess I'll just have a basic area and once local ressources get thin I build smelting outposts directly at the mining sites as processed material only takes half the space

this cuts down size of my main factory significantly too because I fail to build as compact as I'd like

I'm still noob and finding out stuff on my own but getting the basics right is just too essential to me to butcher my whole factory

KatherineOfSky (author) on August 07, 2020:

Thank you so much! I really appreciate the compliment!

franciscocabral on August 03, 2020:

I just love your tutorials, keep doing this amazing job.

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