Rust furnace calculator
Enter your ore and pick a furnace. You get the smelting time, the wood it burns and the charcoal you get back.
How the numbers work
Since 2023 a furnace smelts at a fixed speed no matter how you split the ore, so only the furnace type matters. A small furnace does 0.3 metal ore per second, a large furnace 1.5 and an electric furnace 0.5. Sulfur ore smelts twice as fast as metal ore, high quality metal ore twice as slow.
Furnaces burn 0.5 wood per second and each burnt wood has a 75% chance to drop charcoal, so the charcoal figure is an average. Electric furnaces need 3 power and no wood. Times assume the ore types are smelted one after another and that several furnaces share the ore evenly.
Smelting speed per furnace
| Furnace | Metal Ore | Sulfur Ore | High Quality Metal Ore | 1,000 wood smelts |
|---|---|---|---|---|
| Furnace | 3.33 s | 1.67 s | 6.67 s | 600 Metal Ore |
| Large Furnace | 0.67 s | 0.33 s | 1.33 s | 3,000 Metal Ore |
| Electric Furnace | 2 s | 1 s | 4 s | – |
Seconds per ore. Crude oil goes into a Small Oil Refinery (3.33 s / Crude Oil).
Values checked against Rust Labs on , current for the Livestock update.
Frequently asked questions
How long does a large furnace take to smelt 1,000 metal ore?
About 11 minutes. A large furnace smelts 1.5 metal ore per second and burns roughly 333 wood doing it. A small furnace needs about 56 minutes for the same ore.
Does splitting ore in the furnace still make it faster?
No. Since 2023 the furnace has a fixed speed, so splitting stacks only changes how many slots you fill.
How much charcoal do I get from wood?
Each wood burnt has a 75% chance to give one charcoal, so 1,000 wood gives about 750 charcoal on average.
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