A tick is one cycle of the game loop.
The game loop runs at 20 ticks per second, so one tick counts as 1⁄20 of a second, or 0.05 seconds. An in-game day lasts 24,000 ticks or 20 minutes. Ticks do not affect the game's FPS.
On every game tick, all chunks within the render distance of a player and within 128 of a player are ticked.
This can have various effects.
- During a thunderstorm, lightning will strike somewhere in that chunk (1⁄100000 chance).
- 1⁄16 chance that one column of the chunk is chosen for weather checks on the topmost block.
Chunks are split into 16 sections, each one a 16×16×16=4096 block cube. On every game tick, three blocks (or whatever
/gamerule randomTickSpeed is set to) are chosen from each section in the chunk. The chosen blocks are given a "block tick." Various things can happen, like crops growing, fire spreading, ice melting, etc.
Since block ticks are generated randomly, there is no way to predict when a block will receive its next tick. The median time between block ticks is 47.30 seconds in Java Edition, and 141.94 seconds in Bedrock Edition. The average time between block ticks is 68.27 seconds in Java Edition, and 204.8 seconds in Bedrock Edition.
A Redstone tick spans the length of two game ticks, so one Redstone tick counts as 1⁄10 of a second or 0.1 seconds. By default, a Redstone line doesn't take any time to travel, but a Redstone repeater increases the delay by 1-4 ticks, depending on what it is set to.