A small furnace is fine for your first few hundred ore. The moment you come home with a full inventory of metal and sulfur, it becomes the slowest thing in your base. The Large Furnace fixes that: five ore slots on one shared fire, five times the output and a fraction of the wood per bar.
This Large Furnace Rust guide covers the craft cost, every way to unlock or buy one, where you can and cannot place it, the exact smelting rates, the wood and charcoal maths, how it compares to the standard and electric furnaces, what it takes to destroy one, and the habits that keep it smelting while you farm.
- What It Is
- Stats
- How to Get One
- Placement
- Smelt Rates
- Wood & Charcoal
- Vs Other Furnaces
- Health & Raiding
- Tips
- FAQ
What Is the Large Furnace in Rust?
The Large Furnace is a big, wood-burning smelter. Like the standard furnace, it turns metal ore into metal fragments, sulfur ore into sulfur and high quality metal ore into HQM. The difference is scale. It has five ore slots that all smelt at the same time from one central fire, so a single load can be 5,000 ore and the output per minute is five times higher.
That shared fire is also why it is so wood efficient. In a small furnace the wood burns whether one ore or a full stack is cooking. In a Large Furnace that same flame is cooking five slots, so each bar costs far less wood. For groups, quarry owners and anyone running a jackhammer with Ore Tea, it is the furnace that actually keeps up.
The trade-off is placement. A Large Furnace is too big to go on your foundations, so it has to sit on the ground, usually next to the base with walls built around it.
Large Furnace Stats
| Stat | Value |
|---|---|
| Craft cost | 600 Wood, 500 Stone, 75 Low Grade Fuel |
| Workbench | Level 2 |
| Research table | 60 scrap |
| Tech tree | 250 scrap (Workbench 2 tree) |
| Outpost price | 350 scrap (Building vending machine) |
| Capacity | 5 ore slots (5,000 ore), 2 wood slots (2,000 wood), output slots |
| Metal / Sulfur / HQM | 90 / 180 / 45 per minute |
| Health | 1,500 HP |
| Decay | About 8 hours outside, longer when walled and roofed |
| Placement | Open terrain only, not foundations, floors or caves |
| Recycle | 360 Wood, 300 Stone, 45 Low Grade Fuel |
| Shortname / Item ID | furnace.large / -1992717673 |
The item ID is also in our full Rust item IDs list, useful if you run a server and want to spawn one in.
How to Get a Large Furnace
There are three ways to get your first one, and which is best depends on what you have on hand.
- Research it. If you loot or buy a Large Furnace, put it in a research table with 60 scrap to learn the blueprint for good.
- Tech tree. It sits on the Workbench 2 tree for 250 scrap plus whatever nodes lead to it. Our Rust tech tree guide shows the full path.
- Buy one at Outpost. The Building vending machine sells a finished Large Furnace for 350 scrap. No blueprint and no Workbench 2 needed, which makes it the fastest route on a fresh wipe.
Once you have the blueprint, every extra furnace is 600 wood, 500 stone and 75 low grade fuel at a Workbench 2. The low grade is the part that catches people out, so refine some crude or craft it from fat and cloth before you start.
Where You Can Place a Large Furnace
This is the rule that trips up every new player: the Large Furnace can only be placed on open terrain. It will not go on a foundation, a floor or inside a cave build zone. You have to put it on the ground and build around it.
- Plan the spot before you build. Leave a patch of flat ground beside your base, or inside a compound, for the furnace.
- Wall it in. Place the furnace first, then put foundations around it and raise walls and a roof so it sits in its own smelting room.
- Keep it in tool cupboard range. Out in the open it decays in about 8 hours. Walls, a roof and a stocked cupboard stop that.
- It cannot be picked up. If it is in the wrong place you have to destroy it and craft another, so get the spot right the first time.
- It glows. A lit furnace is a beacon at night, another reason to close it in.
Large Furnace Smelting Rates
Each slot smelts at the same speed as a small furnace. The Large Furnace just runs five of them in parallel, so its total output is five times higher.
| Ore | Per minute | 1,000 ore takes | Small furnace |
|---|---|---|---|
| Metal Ore to Fragments | 90 | About 11 minutes | 18 a minute |
| Sulfur Ore to Sulfur | 180 | About 6 minutes | 36 a minute |
| HQM Ore to HQM | 45 | About 22 minutes | 9 a minute |
Sulfur smelts twice as fast as metal and HQM is the slowest by far. A full 5,000-ore load of metal takes a little under an hour, which is about the time it takes to go out and mine the next load.
Wood Use and Charcoal
Wood is where the Large Furnace really earns its cost. Smelting 1,000 metal ore takes about 330 wood in a Large Furnace against roughly 1,670 wood in a small furnace with all the ore in one slot. Per ore that is about 0.33 wood for metal, 0.17 for sulfur and 0.67 for HQM. On a big ore haul the wood you save pays back the 600 wood the furnace cost almost straight away.
It still makes charcoal. Every piece of wood burned has about a 75% chance to leave one charcoal, and charcoal plus sulfur is gunpowder, 30 charcoal and 20 sulfur for 10 powder. Smelt your sulfur in a Large Furnace and you get the sulfur and the charcoal for your boom in the same load.
Large Furnace vs Furnace vs Electric Furnace
| Furnace | Large Furnace | Electric Furnace | |
|---|---|---|---|
| Cost | 200 Stone, 100 Wood, 50 LGF | 600 Wood, 500 Stone, 75 LGF | 200 Metal Fragments, 5 HQM |
| Workbench | None | Level 2 | Level 2 |
| Metal per minute | 18 | 90 | 30 |
| Fuel | Wood | Wood | 3 power |
| Charcoal | Yes | Yes | No |
| Health | 500 HP | 1,500 HP | 500 HP |
| Placement | Foundations and floors | Open terrain only | Foundations and floors |
A solo early wipe is fine with one or two small furnaces. Once you are bringing back thousands of ore at a time, a Large Furnace is the best value for both time and wood. An electric furnace fits a wired main base, but it makes no charcoal, so most groups end up with a Large Furnace for bulk metal and sulfur plus electric furnaces inside for steady smelting.
Large Furnace Health and Raid Cost
The Large Furnace has 1,500 HP, three times a small furnace. Destroying one takes roughly:
- About 3 C4 (about 6,600 sulfur)
- About 5 rockets (about 7,000 sulfur)
- About 147 explosive 5.56 rounds (about 3,675 sulfur)
Raiders rarely blow the furnace itself. They go through the walls around it to reach the ore and fragments inside, which is why the walls matter more than the furnace HP. Check any wall with our Rust raid calculator, and never leave a finished load sitting in the output slots overnight.
Left outside a building, a Large Furnace decays in about 8 hours. If you tear one down in a recycler you get 360 wood, 300 stone and 45 low grade back, 60% of the cost.
Large Furnace Tips
- Fill every ore slot. All five smelt at the same time, so split the ore evenly instead of stacking one slot.
- Leave output space. If the output slots fill with fragments and charcoal, smelting stops. Empty it or leave a few slots clear before you log off.
- Match the wood to the ore. About a third as much wood as metal ore is enough. Extra wood only makes charcoal.
- Automate it. Industrial conveyors can push ore and wood in from a box and pull fragments and charcoal out, so the furnace runs without you.
- Pair it with fast mining. Ore Tea and a jackhammer fill your inventory fast. A Large Furnace is the only wood furnace that keeps up.
- Buy it on day one. If you have 350 scrap from a monument run, the Outpost furnace saves the tech tree grind.
- Remember the wipe. The furnace, the blueprint and every bar in it reset with everything else. Check when the next force wipe is before you build a big smelting room.
Large Furnace FAQ
How much does a Large Furnace cost in Rust?
It costs 600 wood, 500 stone and 75 low grade fuel to craft at a Workbench 2. You can also buy a finished one at Outpost for 350 scrap.
How do you get the Large Furnace blueprint?
Research a Large Furnace at a research table for 60 scrap, or unlock it on the Workbench 2 tech tree for 250 scrap.
Why can I not place my Large Furnace?
The Large Furnace can only be placed on open terrain. It cannot go on foundations, floors or in cave build zones. Place it on the ground first and then build walls around it.
How fast does a Large Furnace smelt?
With all five slots running it smelts 90 metal fragments, 180 sulfur or 45 high quality metal a minute, five times a standard furnace. 1,000 metal ore takes about 11 minutes.
How much ore does a Large Furnace hold?
It has five ore slots, so it holds 5,000 ore in one load, plus two wood slots for up to 2,000 wood.
How much wood does a Large Furnace use?
About 330 wood per 1,000 metal ore, 170 per 1,000 sulfur ore and 670 per 1,000 HQM ore. A standard furnace with all the ore in one slot needs about 1,670 wood for 1,000 metal ore.
How many C4 does it take to destroy a Large Furnace?
About 3 C4, 5 rockets or 147 explosive 5.56 rounds. It has 1,500 HP.
Is the Large Furnace better than the electric furnace?
For bulk smelting, yes. It smelts 90 metal a minute against 30 for an electric furnace and still makes charcoal. The electric furnace needs no wood and can go inside your base, so many groups use both.
Sources and Further Reading
- Craft cost, workbench and placement: Facepunch Wiki, Large Furnace
- Research and tech tree cost, decay and recycle yield: RustHelp, Large Furnace
- Smelt speed and wood per ore: RustClash, Large Furnace
- Outpost vending prices: Corrosion Hour, Outpost Vending Machines
- Smelting and charcoal: Corrosion Hour, Cooking, Smelting and Refining