Load it once, walk away
A furnace stops the second the wood runs out and burns fuel for nothing once the ore is gone. Both waste the same thing: your time. Put in the ore you have and this gives you the wood that runs out at the same moment.
What are you smelting
Ore converts one for one — a thousand metal ore is a thousand fragments, whichever furnace you use. What changes is the time and the wood.
Put this in
Wood is rounded up to the next whole log, because you cannot load two thirds of one.
Ratio: 166.50 wood per 100 ore.
Wood you already have
Handy when the wood is the scarce half: how much ore one stack of logs actually gets through.
Your furnace, your rates
These three constants are community-measured, not published by Facepunch, and a modded server changes them anyway. Time a burn yourself and type what you saw — every figure above follows what is in these boxes.
Default 3.33
Default 0.5
Default 0.75
One ore becomes one refined unit — that part is uncontested. The smelt times and burn rate are community measurements republished by the rustlabs mirror and repeated by rustly and XGamingServer; they agree with each other and with a single rate of one wood every two seconds, which is why they are usable at all. Charcoal per wood is a measured average, not a game constant. Checked 12 August 2026 — and left editable above so you never have to take our word for it.