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 commonly expressed as the number of block layers above the bottom of the game environment, which is layer zero (0). For instance, sea level is recognized as block layer 62, and clouds appear at layer 127.

Altitude may also be expressed as the bottom face of the block layer, the bottom most of which is at Y-coordinate 0, or Y=0. Sea level would appear at Y=63, and cloud level would appear at Y=128. The player can press to see the Y-coordinate of the top face of the block on which they are standing, and the Y-coordinate of their eyes, which are located about 1.6 blocks above their feet. For example, a player standing at sea level will see the Y-coordinate of their eyes as approximately 64.6.

Limits


The top of the game environment is layer 255, and the top face of the highest block that can be placed is at Y=256. In Pocket Edition, this limit is half, at layer 127 (Y=128), due to limits in the processing power of mobile devices. Attempting to build above this limit will cause the game to display this message: Height limit for building is 256.

The maximum height a player can possibly reach is Y=2,147,483,647, which is the largest value of a signed integer on a 32-bit system. Beyond this limit, the game may become unresponsive or even crash. The highest achievable height in Console Edition is y=511.

In contrast, any player who falls below the altitude of Y=-64 will receive damage every half second and eventually die, even in Creative mode. However, if a player is made invincible, they will continue to fall well beyond this limit.

Natural resources and altitude
Features in the landscape of the Overworld are found at different altitudes, as shown in the graph below. There is also an interactive chart.



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 layers 13-14.

See the following table for a textual description of resources by altitude and tools needed to gather them.

Other naturally occurring features appear at different altitudes, but all of these features are random and will only appear in conjunction with another block and the proper environment.

The Nether
A similar graph, showing the distribution of blocks unique to the Nether:



Trivia

 * The highest possible altitude the player can legitimately climb to is Y=257 (via the door "glitch" + jumping), although explosions can blast the player far beyond this limit.
 * Although blocks cannot normally be placed past Y=254, there are several exceptions:
 * Beds, along with other non-solid blocks (signs, torches) can be placed on the 255th layer. Also, if a door is placed 1 layer below the top of the map, its upper frame will pass the 254th mark.
 * By placing a water source block on layer 255 using a water bucket on a solid block on layer 254, then placing a lava source block on the water using a lava bucket, both cobblestone and obsidian can be created on layer 255. The opposite (placing water on lava) works as well.
 * Placing a rail, flat snow, etc. block on the 255th layer, then trying to place a block on it will give you the message: Height limit for building is 256. This also applies when trying to place a block on top of a solid block at layer 255 (using MCEdit, or water and lava).
 * Mushrooms can spawn on the 129th layer in the Nether, above the bedrock.