Smelting and fuel calculator
Work out how much fuel a smelting job needs and how long it takes, with one furnace or a whole row of them.
- Fuel needed
- Time
- Per furnace
How to use it
Enter how many items you want to smelt, pick your fuel and furnace type, and set how many furnaces you'll run side by side. The calculator shows the fuel to bring, how long the job takes, and whether any fuel goes to waste.
How much each fuel smelts
| Fuel | Items smelted | Burn time |
|---|---|---|
| Lava bucket | 100 | 1,000 s |
| Block of coal | 80 | 800 s |
| Dried kelp block | 20 | 200 s |
| Blaze rod | 12 | 120 s |
| Coal or charcoal | 8 | 80 s |
| Boat | 6 | 60 s |
| Log, wood or planks | 1.5 | 15 s |
| Wooden slab | 0.75 (Java), 1.5 (Bedrock) | 7.5 s (Java) |
| Stick, sapling or wool | 0.5 | 5 s |
| Bamboo or scaffolding | 0.25 | 2.5 s |
A block of coal smelts 80 items, while the 9 coal it's made from would smelt only 72. Crafting coal into blocks is a free 11% bonus.
Furnace, blast furnace or smoker?
- Furnace: 10 seconds per item, smelts anything.
- Blast furnace: 5 seconds per item, but only ores, raw metals and metal tools and armor.
- Smoker: 5 seconds per item, but only food.
Blast furnaces and smokers burn fuel twice as fast as they smelt, so each piece of fuel still covers the same number of items. You save time, not fuel.
Tips for big jobs
- Split across furnaces. Eight furnaces fed by hoppers finish a stack of 64 in 80 seconds instead of over 10 minutes.
- Use lava for long jobs. One bucket runs a furnace for over 16 minutes, and you get the bucket back.
- Kelp farms are renewable fuel. A dried kelp block smelts 20 items, and kelp grows on its own underwater.
- Avoid waste with odd fuels. Fuel that smelts a fractional number of items, like logs (1.5), leaves part of the last piece unused. The calculator shows how much.