Minecraft Smelting Calculator
Editions: Java + Bedrock (fuel values shared) · Verified: Java 26.3 / Bedrock 26.50 · 2026-09-16 · Updated 2026-09-16
A furnace smelts one item every 10 seconds and every fuel is just a number of those ten-second windows. Enter the job, pick a fuel, and get whole fuel units — rounded up the way the furnace actually consumes them — plus the honest clock across however many furnaces you run.
The worked example
Say a branch-mining haul leaves 700 items of raw iron and copper to cook. On coal that is 700 ÷ 8 = 87.5, which the furnace consumes as 88 whole coal — the half piece burns anyway. The same job is 9 blocks of coal, 35 dried kelp blocks, or just 7 lava buckets. On one furnace it runs 7,000 seconds — 1 hour 56 minutes 40 seconds — while eight furnaces fed evenly finish in 880 seconds, under fifteen minutes. Fuel counts always round up; the tool also shows how much of the last unit's burn goes spare.
Every fuel, one honest table
| Fuel | Burn time | Items smelted |
|---|---|---|
| Lava bucket | 1,000s | 100 |
| Block of coal | 800s | 80 |
| Dried kelp block | 200s | 20 |
| Blaze rod | 120s | 12 |
| Coal / charcoal | 80s | 8 |
| Planks (any wood) | 15s | 1.5 |
| Stick | 5s | 0.5 |
| Bamboo | 2.5s | 0.25 |
Values verified against the Minecraft Wiki's smelting documentation; each burn time is taken from there and each items-per-fuel figure derived from it, and every row is asserted in our test suite. The fuel guide covers which of these you should actually farm.
Questions builders actually ask
How many items does one piece of coal smelt?
Eight. Coal and charcoal burn 80 seconds and a furnace smelts one item every 10 seconds. Up the ladder: a blaze rod smelts 12, a dried kelp block 20, a block of coal 80, and a lava bucket 100 — and the empty bucket comes back.
Is a block of coal better fuel than nine coal?
Yes. Nine coal smelt 72 items as loose pieces, but crafted into a block they burn 800 seconds and smelt 80 — the block burns like ten coal while costing nine. Blocking your coal is a free 11 percent, as long as the furnace runs long enough to use the whole burn.
How long does a big smelting job take?
Ten seconds per item, per furnace, so one furnace does 360 an hour. A full double chest of 64-stacks — 3,456 items — is 9.6 hours on one furnace but under an hour on ten. The calculator splits the load with the busiest furnace deciding the finish time.
Does this cover blast furnaces and smokers?
The fuel counts do: those blocks smelt eligible items twice as fast but consume fuel twice as fast too, so items-per-fuel stays the same. Only the times shown here would halve. The calculator models the regular furnace clock and says so.