Furnace

Overview

The furnace is the block that turns raw material into usable material, and almost nothing in Minecraft happens without one. It smelts ore into ingots, sand into glass, clay into brick, logs into charcoal, raw meat into cooked, cobblestone into stone, and stone into smooth stone. One item takes 10 seconds, and the fuel economy is worth memorising: one coal or charcoal smelts 8 items, a block of coal smelts 80, a lava bucket 100, a dried kelp block 20, and any wooden item smelts 1.5 — which is why wooden stairs and leftover saplings are perfectly good fuel. Smelting grants experience when you collect the output, and the experience is stored in the furnace until you do, so a furnace left running for hours hands over a large lump of levels at once. A furnace is also the Armorer, toolsmith and weaponsmith villager job site block in some cases, and it is one of the two blocks that a comparator can read the progress of. Since 1.14 the blast furnace and the smoker split its job in two, each doing half the recipe list at twice the speed.

Smelting ore into ingots, sand into glass, logs into charcoal and food into cooked food — the single most-used utility block in the game, and a store of experience until you collect the output.

In Minecraft 1.21.4, Furnace is a functional block. Furnace has a crafting recipe, so it is renewable as long as you can source its ingredients. At hardness 3.5 this is one of the tougher blocks in the game.

It needs at least a wooden pickaxe to drop anything; a weaker tool destroys it for nothing. Mining it returns the block itself, so it is safe to relocate. A full stack holds 64.

It is crafted from Cobblestone. You will need it for Blast Furnace, Minecart with Furnace, and Smoker.

How to get it

Craft it from 8 cobblestone, which is available within the first minute of any world. Furnaces also generate in villages, igloos and woodland mansions, usually already stocked with something.

Tips

1 coal smelts 8 items, a lava bucket smelts 100, and a dried kelp block smelts 20 — kelp is the renewable choice.
Experience accumulates in the furnace until you take the output, so empty a long-running furnace in 1 go for the levels.
Use a blast furnace for ores and a smoker for food: both are twice as fast, at the cost of half the experience.
Feed it with hoppers from above for input, from the side for fuel, and from below to collect — that is the standard array.

How long it takes to break

At a hardness of 3.5, Furnace takes 18 seconds to punch out and 0.6 seconds with a netherite-tier tool of the correct class.

An iron tool takes 0.9 seconds and a diamond one 0.7, so the jump that actually matters for this block is the one to iron.

A weaker tool still breaks it, but anything under wooden returns nothing — you spend the time and lose the drop, which is how most veins get wasted.

The Efficiency formula is level² + 1 added to tool speed — at V that is about 4 times the unenchanted rate.

* breaks the block but yields no drop
Tool	No enchantment	Efficiency III	Efficiency V
Hand *	18 s	18 s	18 s
Wooden	2.7 s	0.45 s	0.2 s
Stone	1.4 s	0.4 s	0.2 s
Iron	0.9 s	0.35 s	0.2 s
Diamond	0.7 s	0.3 s	0.2 s
Netherite	0.6 s	0.3 s	0.15 s
Golden	0.45 s	0.25 s	0.15 s

Properties

With 3.5 blast resistance Furnace usually goes down to a nearby explosion. It is fully opaque and produces no light. 64 fit in a slot — a full stack. The block is tagged for pickaxes, and only that class gets the speed bonus; everything else mines at bare-hand rate.

Transparent: No
Required tool: Wooden Pickaxe