Altitude



Altitude is a measurement of vertical distance, or distance along the Y-axis.

Definition
Altitude is defined as "the height of anything above a given planetary reference plane, especially above sea level on earth."

In Minecraft, altitude is often expressed as the bottom face of a block layer, where the lowest block that can be placed is at layer 0 and has a Y-coordinate of 0 (in Java Edition 1.18 and Bedrock Edition 1.18.0, this Y-coordinate is −64). For instance, sea level is at layer 62, while clouds appear at layer 127 (in Java Edition 1.18 and Bedrock Edition 1.18.0, clouds appear at layer 191).

This is not to be confused with altitude when otherwise expressed as the top face of a block layer, where the lowest block that can be placed is at layer 1 and has a Y-coordinate of 1. For example, sea level is at layer 63, while clouds appear at layer 128. This is akin to calling the ground level storey the "first floor" (top face of a block layer), rather than the "ground floor" (bottom face of a block layer). The player can press to see the Y-coordinate of the top face of a block they are on top of.

Altitude expressed as the bottom face of a block layer is most useful for identifying the position of blocks, such as when using to replace block(s). Expressing altitude as the top face of a block layer is more useful for identifying the position of entities, such as when using to teleport or  to spawn an entity/entities. For instance, the topmost block of water in an ocean biome has a Y-coordinate of 62; in a frozen ocean biome, ice replaces water at sea level, and the lowest height where terrestrial mobs will spawn is at layer 63.

Natural resources and altitude
Features in the landscape of the Overworld are found at different altitudes, as shown in the graph below.



Note that these charts utilize the logarithmic scale, which means a slight difference in the Y-coordinate represents a large change in the relative frequency of a block type.

Some observations:
 * Looking at water, the amount at layer 62 (sea level) is obvious. Moving down, the amount quickly decreases at layers 56 and 48, the usual depth of river and ocean biomes respectively.
 * There are corresponding peaks in the amount of clay beneath them.
 * Between layers 33 and 12, most water is falling down sub-ocean ravines, spreading out on the lava-filled bottom at layer 10 and producing most of the naturally-occurring obsidian.
 * Ores and gravel (not shown) usually occur as a fixed percentage of the amount of stone (also not shown), tapering off at the ends of their allowed generation range.
 * This is why coal and iron follow parallel tracks between layers 5 and 60.
 * The one exception is lapis lazuli ore, which has a linear progression up to a peak at Y = 15.

The following table offers a more in-depth summary of the same block distribution as shown in the graph above.

The Nether
A similar graph, showing the distribution of blocks unique to the Nether (Java Edition 1.16.4):



The following table offers a more in-depth summary of the same block distribution as shown in the graph above.

The End
A similar graph, showing the distribution of blocks unique to the End (Java Edition 1.16.4):



The following table offers a more in-depth summary of the same block distribution as shown in the graph above.

Trivia

 * The highest possible altitude the player can legitimately climb to is Y = 256, although explosions, elytra launchers, piston slime block bounces, and Riptide tridents can all propel the player far beyond this limit.
 * $$, mushrooms can appear on the Nether's bedrock ceiling.
 * Block generation and player construction below and above the build limits can be achieved only through modifying the dimension properties, or mods, such as the Cubic Chunks mod.
 * The reasoning behind Custom worlds having height limits of ±2032 rather than ±2048 (a binary number notated as ) is because the lighting system still applies 16 blocks above and below the world, but the Y-coordinates of blocks (which are also used in the lighting calculation) are stored internally using only 12 bits. Therefore, having limits of ±2048 would prevent the lighting system from functioning correctly.