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Rust Smelting Calculator
A furnace smelts 3 metal ore every 10 seconds, a large furnace five times that. Pick a smelter and enter your ore to see how long it takes, how much wood it burns and how much charcoal you get back. Splitting ore doesn't speed it up any more - every slot shares the furnace's speed.
Your smelt
Result
Smelters compared
| Smelter | Ore slots | Fuel | Speed | Notes |
|---|---|---|---|---|
 Furnace | 2 | Wood | 3 metal ore / 10 s | 1,000 wood burns for 33 min - about 600 metal ore. |
 Large Furnace | 5 | Wood | 5x the furnace | Five times the furnace's speed for the same wood - five times more wood-efficient. |
 Electric Furnace | 2 | Electricity (3 power) | 5/3 of the furnace | No wood and no charcoal. Switches on and off with its power. |
 Small Oil Refinery | 1 | Wood | 3 crude / 10 s | Each crude oil makes 3 low grade fuel. |
Smelting tips
- Splitting ore no longer speeds anything up: since Rust's October 2022 oven rework all input slots smelt at once and share the oven's speed. Use more furnaces, or a large furnace, to smelt faster.
- Smelting is 1:1 - metal ore to metal fragments, sulfur ore to sulfur, high quality metal ore to HQM. Crude oil gives 3 low grade fuel.
- Charcoal comes from the wood burned, not from a recipe: each wood has about a 75% chance to leave 1 charcoal, so a furnace makes about 22 charcoal a minute.
- A full output stops the oven - HQM stacks to 100, so a small furnace fills up fast on HQM ore.
- Ovens keep burning after the ore runs out until the fuel does - take the wood out or switch it off.
- Modded servers (quick smelt and similar) change all of these numbers.
Values checked 2026-11-07 against wiki.facepunch.com, wiki.facepunch.com, wiki.facepunch.com, wiki.facepunch.com. Server mods can change smelt speed.
The Rust smelting calculator works out how long a furnace, large furnace or electric furnace takes to smelt your metal ore, sulfur ore and high quality metal ore, how much wood it burns and how much charcoal you get back - plus crude oil into low grade fuel at the small oil refinery. Set how many smelters you're running to see how much faster a row of furnaces gets it done.