NapNodes
Free tool · Minecraft Java

Furnace fuel calculator: fuel and time

Type how much you're smelting or cooking and we tell you how much coal, logs, lava or whatever you have it takes, and how long it lasts in a furnace, blast furnace or smoker. With several furnaces at once, too.

How much are you smelting or cooking?

A number (“64”, “500”) or in stacks (“3 stacks and 20”, “1 sb”).

In what?

How many at once?

64 items

It takes 10 min 40 s.

FuelYou needLeft over for
Lava bucket136
Block of coal116
Dried kelp block416
Blaze rod68
Coal8—
Charcoal8—
Boat (any)112
Log43—
Planks43—
Wooden slab86—
Stick128—
Sapling128—
Wool128—
Carpet192—
Bamboo256—
Scaffolding256—
Build the smeltery on your free server

A Minecraft server for you and your friends, 3 GB and no card.

The maths it does

  • Furnace: 10 seconds per item. Blast furnace (ores and metal) and smoker (food): 5 seconds, with the same fuel per item.
  • Lava bucket: 100 items. Block of coal: 80. Dried kelp block: 20. Blaze rod: 12.
  • Coal and charcoal: 8. Boat: 6. Log and planks: 1.5. Stick, sapling and wool: 0.5. Bamboo and scaffolding: 0.25.

Inside one furnace, whatever is still burning from a fuel carries on with the next item; if the furnace runs empty, the rest goes out and is lost. That's why the “Left over for” column tells you how many more you could have put in without spending more.

A smeltery for the whole server

  1. Put several furnaces in a row with hoppers on top fed from a chest, and another hopper on the side with the fuel.
  2. Underneath, hoppers that carry the output to a shared chest: everyone drops off their iron and takes ingots.
  3. With an automatic kelp farm (made into dried kelp blocks) or a bamboo farm, the fuel takes care of itself. And smelting XP is collected when you take items out: count it with the XP calculator.

Frequently asked questions

How much coal do I need to smelt a stack?

One coal smelts 8 items, so 64 take 8 coal. A block of coal (80 items) leaves enough for 16 more. Charcoal lasts exactly as long as coal.

How many items does a log smelt?

1.5, the same as planks. So crafting it into planks pays off: one log makes 4 planks, which smelt 6 items. Better still, make charcoal: a log in the furnace gives one charcoal, which smelts 8.

How long does a lava bucket last in a furnace?

100 items: 16 min 40 s in a regular furnace. It's the longest-lasting fuel, and the empty bucket stays in the fuel slot so you can refill it.

Does a blast furnace use more fuel?

It's twice as fast (5 seconds per item instead of 10) and burns fuel twice as fast, so each coal still smelts 8 items. Same fuel, done sooner. It only smelts ores, raw metal and metal gear, though; the smoker, only food.

How do I smelt faster?

With several furnaces at once, splitting the load: with 8 furnaces, 64 iron are done in 1 minute 20 seconds. Pick how many in the calculator: each furnace burns its own fuel, so what's left in one doesn't carry over to another.

Does the smeltery stop when the host logs off?

In a world opened from one person's computer, furnaces only run while that person is playing. With a server, the world stays there for everyone even when they're away. At NapNodes the RAM in your plan is yours alone and each machine's load is public on the status page. Try it with a free 3 GB Minecraft server, no card and no end date.

Create your free server

Storing what you smelt? Count chests and shulker boxes with the stack calculator.

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