How does TNT duping work in Minecraft?

TNT duping happens when Minecraft players trick the game into thinking there are more TNT blocks than there actually are. TNT duping is an important part of the Minecraft community, a tool used by griefers, miners, and others.

Many of the game’s more technical players have devised ways to create all sorts of automatic TNT duping systems, which players can use to destroy blocks in a much more efficient manner.

TNT duping has been removed from Minecraft several times and is considered a form of cheating by many of the most popular Minecraft SMPs, streamers, and servers.

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Understanding TNT duping in Minecraft

An image of TNT falling from a sky in Minecraft. Image via Minecraft.

TNT duping works when players use specific Minecraft mechanisms to exploit some of the game’s quirks. Players often use a Block Update Detector (also called a BUD or BUD switch).

BUD switches are redstone mechanisms that utilize some of the game’s mechanisms to detect changes in nearby blocks. Players can make one of them out of a sticky piston, a few slime blocks, a lever, and a redstone block. Some simple modifications are required to turn it into a TNT duper.

Because of the nature of BUD switches, Minecraft players who make TNT dupers tend to build them free-floating above the ground. This is so that the BUD switch doesn’t detect any unwanted block updates, which might break a player’s TNT duper.

When they ignite a TNT block connected to a BUD switch, Minecraft players can trick the game into thinking that that block is an entity and an object that's being moved at the same time. The TNT block is being updated, but neither it nor the game knows it. This glitch keeps the TNT block from being deleted and is why Minecraft duplicates the TNT.