Furnace Fuels

To smelt or cook anything in minecraft, you need a furnace and some fuel. The fuel you use can range from simple wooden blocks, to coal, lava buckets or even blaze rods. However, not all blocks are equally useful, some will burn longer than the other, while some are simply too difficult to get.

In this guide we will explain which fuels are the most efficient in terms of time. As some fuels, like lava buckets, will burn for a long time, but they may not always be the best option for you, as it could take a while to find enough lava source blocks and enough iron for the buckets.

List of fuels

Lava bucket
Blaze rod
Charcoal
Coal
Bookshelf
Chest
Crafting table
Fence
Huge mushroom blocks
Jukebox
Noteblock
Pressure plates (wooden)
Trapdoors
Wood
Wooden planks
Slabs (wooden)
Stairs (wooden)
Wooden tools and swords
Saplings
Sticks

Lava bucket efficiency

First the lava bucket. While its 1000 second burning time is great, the disadvantages far outweight this advantage. A bucket of lava requires a lava source block and a bucket, which is made out of 3 iron ingots. While this may not be an issue when you’re deep underground with a big supply of iron, just the fact that you lose the bucket, and thus 3 iron ingots, is already enough to lower the efficiency. It takes way too long to find the lava and the iron to make the lava bucket an efficienct fuel, but if you do happen to have one lying around, its 1000 seconds burning time is quite decend.

However, remember that you can only put 1 stack of items in the furnace at a time, so you can’t even use the 1000 second burning time without having to come back at least once.

Coal vs charcoal

It may seem weird that coal is less efficient than charcoal, but this has to do with the time it takes to aquire the same amount of each item.
Trees are generally way more widely available and renewable, while coal requires more effort and a bit of luck to find in large quantities. This makes charcoal generally a much more efficient fuel than coal, as long as you keep replanting saplings of course.

Charcoal vs wooden planks

Based on burning time and farming time, charcoal is less efficient than wooden planks. Charcoal burns for 80 seconds, but it’s made by first burning a log for 10 seconds. That same log could be turned into 4 planks, which’ll burn for a total of 60 seconds. This means 4 planks could smelt 6 items, as it takes 10 seconds to smelt 1 item. A lump of charcoal lasts 80 seconds, which smelts 8 items, but you have to add the 10 seconds it takes to burn a log to create the charcoal.

This means that 1 item takes 11.25 seconds (90 seconds / 8 items) to be cooked if you use charcoal (and start from a log), while wooden planks will only take 10 seconds per item. The 11.25 seconds will always be the same, no matter how many items you smelt.
This makes charcoal less efficient than planks, though this is more apparent when you smelt larger quantities of items.

Say you need to smelt 300 cobblestone into stone for your castle walls. 300 cobblestone would require 200 planks, which equals 50 logs. The total time it takes you to smelt the cobblestone (in a single furnace) equals 3000 seconds, or 50 minutes. Those same 300 cobblestone would require 38 charcoal (37.5 to be exact). Those 38 charcoal require 380 seconds worth of fuel to be created, on top of the 3000 seconds it takes to smelt the cobblestone. So creating the charcoal and then smelting the cobblestone would take a total of 3380 seconds, or 56.3 minutes.

Wooden slabs, the best fuel.

Wooden slabs are by far the best and most efficient fuel in minecraft for the simple reason that you can make a lot of them out of just a few logs.
3 logs make 12 planks, which in turn create 24 wooden slabs, which all burn for 15 seconds. This means just 3 logs give you 360 seconds of burning time, or little over 1/3 of the burning time of a lava bucket.