What do the values on the Minecraft debug screen represent?

Question

If you hit F3 while playing Minecraft, an overlay appears. Some of the items, such as fps, x, y, and z are obvious, but I'm curious about some of the other values. What do they all represent?

Answer 1

Debug numbers

• C is the number of renderers* being rendered over total number loaded
• F is number of renderers being clipped (i.e. not viewable)
• O is the number of renderers removed through occlusion culling
• E (first line) is the number of renderers skipped
• E (second line) is the number of rendered entities over total entities
• B is the number of entities hidden
• I is the number of individually removed entities (the remainder of B and the numerator of E combined)
• P is the number of particles
• T: All is the total number of entities
• MultiplayerChunkCache is the number of chunks currently loaded into memory

• x and z are your current coordinates along the horizontal plane
• y (feet pos) is the current coordinate along the vertical plane of the floor you're walking on
• y (eyes pos) is the current coordinate along the vertical plane of your eye level (Steve's eyes being 1.620 blocks above the ground)
• f is the orientation of Steve: 0 is west, 1 is north, 2 is east, 3 is south
• lc is the height level of the highest non-air block within the current chunk
• b is the name of the biome you're currently in
• bl is the light level of the block your head is in, from block-based lights like torches
• sl is the level of sunlight/moonlight on the block your head is in (independent of the current time of day)
• rl is the maximum of bl and sl
• ws is your walk speed
• fs is your flying speed
• g is whether your feet are on the ground (true if you are, false otherwise)

Graphs

The bar graph charts frame rate over time inversely (e.g., higher spikes = lower frame rate). Green plots are when your frame rate is 60 FPS or higher.

The pie graph charts the distribution of CPU time across different parts of Minecraft:

• [0] root (white) is essentially a sanity check: should always be 100%
• [? probably 1]unspecified (green) is the time spent on things not already enumerated
• [2] render (blue) is the time spent on rendering the world
• [3] tick (purple) is the time spent on the game clock (heartbeat)
• [4] sound (yellow) is the time spent on the sound engine
• [5] updatelights (salmon) is the time spent on updating the lighting engine (usually at sunset and sunrise)

Pressing the 1-9 keys will show sub-divisions of the numbered slices of the pie chart (in addition to switching items as usual), and pressing 0 will go back up.

Notes

• A chunk, if you're not familiar with the term, is a section of the world, equal to 16x128x16 blocks.
• Given the context in which it appears in RenderGlobal.java, I believe "renderers" refers to a single block.
• Under the Minecraft coordinate system, X and Z are the horizontal axes and Y is the vertical axis, which confuses players used to other coordinate systems.

Answer 2

There is a very good video I have of this. It explains the F3 menu / debug screen.