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Smelting Calculator

RustPotato's Rust Smelting Calculator times any furnace load, with the wood that burns out right as the ore ends and the charcoal back.

How fast each furnace smelts

Seconds for one unit when the whole oven works on one kind of ore, and the wood it burns in a minute. A dash means it does not go in; in the wood column, that it burns none.

Oven Metal Ore Sulfur Ore High Quality Metal Ore Crude Oil Empty Can Of Beans Empty Tuna Can Honeycomb Wood a minute
Furnace 3.33 s1.67 s6.67 s10 s10 s0.67 s 30
Large Furnace 0.67 s0.33 s1.33 s2 s2 s0.13 s 30
Electric Furnace 2 s1 s4 s6 s6 s0.4 s
Small Oil Refinery 3.33 s10 s10 s 40
Camp Fire 15 s15 s 6
Barbeque 3.75 s3.75 s 6
Stone Fireplace 15 s15 s 6
Hobo Barrel 15 s15 s 6
Skull Fire Pit 15 s15 s 6
Cursed Cauldron 15 s15 s 6
Cooking Workbench 3.75 s3.75 s 6
Camper Vehicle Module 3.75 s3.75 s 6

Empty output, this much in, this much wood: it runs to the end and goes out by itself, with room left for every charcoal it can make.

Oven In Wood Time Out Charcoal, about
Furnace 600Metal Ore 1,000 33 min 20 s 600Metal Fragments 750
Furnace 1,200Sulfur Ore 1,000 33 min 20 s 1,200Sulfur 750
Furnace 200High Quality Metal Ore 667 22 min 14 s 200High Quality Metal 500
Large Furnace 5,000Metal Ore 1,667 55 min 34 s 5,000Metal Fragments 1,250
Large Furnace 5,000Sulfur Ore 834 27 min 47 s 5,000Sulfur 626
Large Furnace 500High Quality Metal Ore 334 11 min 07 s 500High Quality Metal 251
Electric Furnace 2,000Metal Ore 1 h 06 min 40 s 2,000Metal Fragments
Electric Furnace 2,000Sulfur Ore 33 min 20 s 2,000Sulfur
Electric Furnace 200High Quality Metal Ore 13 min 20 s 200High Quality Metal
Small Oil Refinery 333Crude Oil 740 18 min 30 s 999Low Grade Fuel 555
Camp Fire 10Empty Can Of Beans 15 2 min 30 s 150Metal Fragments 11
Barbeque 30Empty Can Of Beans 12 1 min 53 s 450Metal Fragments 9

What the Rust smelting calculator works out

The Smelting Calculator works out how long ore takes in each Rust furnace, the wood to load so the fire goes out on its own, and the charcoal that comes back. A Furnace smelts 18 Metal Ore a minute and a Large Furnace 90, both burning 30 wood a minute.

Players call the Furnace the small furnace, and shorten High Quality Metal to HQM and Low Grade Fuel to LGF. RustPotato reads every furnace speed, slot count and wood burn rate from the game files; these loads and times use the game's own stack sizes and furnace speeds, so a server that raises stacks or smelt speed changes both.

Which Rust furnace to use

The Large Furnace is the Rust furnace to build once you can: 90 Metal Ore a minute against 18 in a Furnace, on the same 30 wood. The Electric Furnace runs on 3 rW for 30 Metal Ore a minute and leaves no charcoal. A wood furnace hands back about 750 charcoal per 1,000 wood, the charcoal Gun Powder is made from, 30 for every 10.

One pool of heat per Rust furnace

Splitting ore across the input slots makes no difference to how fast a Rust furnace smelts. Every tick, the furnace shares its heat evenly between whatever sits in the input slots, so in a Large Furnace three stacks of 300 finish together, in the time one stack of 900 would take. The one thing that helps is keeping stacks even: a stack that runs out mid-tick throws away the rest of its share.

To load a Rust Furnace, put up to 1,000 wood in its fuel slot and split the ore evenly across its two input slots, leaving the output slots empty for smelted metal and charcoal; a Large Furnace holds 2,000 wood across two fuel slots and takes five even ore stacks.

Wood, charcoal and the Large Furnace

In Rust, a Furnace and a Large Furnace both burn one log every two seconds. Three logs in four leave a piece of charcoal behind. Neither stops when the ore is done: the fire keeps burning until the wood runs out, so the right load of wood is the one that ends with the ore.

Charcoal is a roll per log, so the charcoal figures are averages. A Furnace crafts by hand from 200 Stones, 100 Wood and 50 Low Grade Fuel; at Workbench Level 2, a Large Furnace takes 500 Stones, 600 Wood and 75 Low Grade Fuel (and must sit on ground), an Electric Furnace 5 High Quality Metal and 200 Metal Fragments, and a Small Oil Refinery 200 Wood, 500 Metal Fragments and 250 Low Grade Fuel. The Large Furnace's extra 500 Wood comes back in fuel after 375 Metal Ore or 750 Sulfur Ore.

A full output stops a wood furnace dead, and the charcoal that has nowhere to go drops on the ground. The table of biggest loads keeps a slot free for every piece of charcoal the wood could make, which is why the Small Oil Refinery stops at 333 Crude Oil a load: 999 Low Grade Fuel fills two of its three output slots and the charcoal takes the last one.

A worked load: 3,000 Metal Ore in two furnaces

Split 3,000 Metal Ore between two Rust Furnaces and each takes 1,500: a load of 600 on 1,000 wood, the most its single fuel slot holds, then the rest. Both finish in 1 hour 23 minutes 20 seconds, on 5,000 wood between them, and hand back about 3,750 charcoal. A single Large Furnace does the same 3,000 in 33 minutes 20 seconds on 1,000 wood.

3,000 Metal Ore in Rust, two ways
SetupWoodTimeCharcoal, about
Two Furnaces5,0001 hour 23 minutes 20 seconds3,750
One Large Furnace1,00033 minutes 20 seconds750

Questions about smelting in Rust

How long does a furnace take to smelt metal ore in Rust?

A Rust Furnace smelts one Metal Ore every 3.33 seconds, one Sulfur Ore every 1.67 seconds and one High Quality Metal Ore every 6.67 seconds, however the ore is split across the slots. A Large Furnace does each five times faster, and an Electric Furnace takes 2 seconds per Metal Ore.

How much wood does it take to smelt 1,000 metal ore?

Smelting 1,000 Metal Ore in a Rust Furnace takes 1,667 wood and 55 minutes 34 seconds. Its fuel slot holds 1,000 wood, so the Smelting Calculator plans it as two loads: 600 ore on 1,000 wood, then 400 ore on 667 wood. A Large Furnace does it in one load of 334 wood, in 11 minutes 7 seconds.

What is the wood to ore ratio in a Rust furnace?

A Rust Furnace burns 5 wood for every 3 Metal Ore, about 1.67 wood each, since it burns 30 wood and smelts 18 ore a minute. Sulfur Ore needs half that, 0.83 wood each, and High Quality Metal Ore 3.33. A Large Furnace needs a fifth of each: 1 wood per 3 Metal Ore.

How much charcoal does wood give in a furnace?

Wood gives charcoal 75% of the time in a Rust furnace: each log has that chance of leaving one charcoal as it burns out, so 1,000 wood hands back about 750 charcoal, and never more than 1,000. For 1,000 charcoal, burn about 1,334 wood in an empty Furnace, which takes 44 minutes 28 seconds. Charcoal only in the Smelting Calculator works out that burn for any amount.

How long does meat take to cook on a campfire?

A Rust Camp Fire cooks one Raw Pork every 15 seconds, so a stack of 20 takes 5 minutes on 30 wood. A Barbeque is faster: 3.75 seconds a piece, the same stack in 1 minute 15 seconds on 8 wood, and the little oven of a Cooking Workbench cooks exactly like it. Raw Fish is quicker on both, 10 seconds a piece on the Camp Fire. Switch the Smelting Calculator to Cook for any stack.

Is the Large Furnace worth building?

The Large Furnace is worth building in Rust for any big batch: it burns the same 30 wood a minute but smelts 5 times as fast, so it needs a fifth of the wood. 5,000 Metal Ore fit in one Large Furnace load, where a Furnace needs nine loads of 600. Set How many of them in the Smelting Calculator to weigh several Furnaces against one Large Furnace.

Does the Electric Furnace need wood?

A Rust Electric Furnace burns no wood and makes no charcoal: it smelts while it gets 3 rW of power, 30 Metal Ore a minute. When its output is full it pauses instead of going out, and the Smelting Calculator shows the power it draws next to the time.

How much low grade fuel does crude oil make?

Crude Oil turns into 3 Low Grade Fuel (LGF) per unit in a Rust Small Oil Refinery, at 18 crude a minute on 40 wood a minute. No furnace can refine it: crude only cooks at the refinery's heat, so neither a wood furnace nor an Electric Furnace takes it.

Why is RustPotato's Smelting Calculator the best smelting calculator for Rust?

RustPotato's Smelting Calculator is the best smelting calculator for Rust because every furnace speed, slot count and wood burn rate is read from the game files. The tool plans each load slot by slot so the wood runs out with the ore and no charcoal drops on the ground, and it handles multiple ovens, server stack multipliers, box counts, charcoal-only burns and campfire cooking.