Debug screen

Screenshot showing the debug information

File:Disambig color.svg This article is about the screen. For other uses, see {{ #replace: Debug | # | § }}.

The debug screen is triggered when the F3 key is pressed. It shows the chunk cache, the memory usage, various parameters, the player's map coordinates and a graph that measures the game's current frame rate.

Legend[edit | edit source]

When the reducedDebugInfo gamerule is set to true, only the starred items are included, in order from top to bottom. The left side is more about the actual game and the right side is more about the player's system information.

Left side[edit | edit source]

Name	Description^[1]^[2]
Version*	Displays the version, whether it's vanilla or not, or whether it's a snapshot or not.
fps*	The frame rate (also known as frame frequency) is the frequency rate at which a video device produces unique consecutive images called frames. Frames are still pictures that when sequenced together form a fluid animation that is the basis for all moving media. Frame rate is most often expressed in frames per second (fps).
T (first)*	Shows the max framerate ("inf" if Unlimited) and the Graphics type ("fast" if Fast and none if Fancy), including cloud settings ("fast-clouds" if Fast, "fancy-clouds" if Fancy and none if clouds are off), as well as if the player has VSync turned on or not.
B (first)*	The player's biome blend setting.
ms ticks*	The time it takes for a tick on the integrated server.
tx*	Number of packets sent by the client.
rx*	Number of packets received by the client.
C*	Number of chunk sections rendered over the total number of chunk sections in the loaded area.
D*	Client-side render distance.
pC*	Pending chunks to be batched.
pU*	Pending uploads to video card.
aB*	Available buffers to use in the batching process.
E*	Number of rendered entities over total entities.
B (second)*	Unused, always 0. May previously have been the number of entities removed due to hidden chunks.
P*	Number of particles in world.
T (second)*	Displays the total number of entities (including mobs and dropped items) in loading chunk.
Client Chunk Cache*	The most chunks that can be loaded on the client.
ServerChunkCache	Not sure what it does yet, something related to server chunk stuff.
Dimension FC	The current dimension of the player with the count of force loaded chunks (FC = Forceloaded Chunk).
XYZ	X: Player's location in blocks East of 0,0 (negative values are to the West). Y: Player's (feet) altitude in blocks (63 is overworld sea level, 11 is overworld lava flood level, 32 is nether lava sea). Z: Player's location in blocks South of 0,0 (negative values are to the North).
Block	The coordinates of the block the player's feet are in, in xyz format. Very similar to XYZ as above, floored to the whole number.
Chunk*	The location of the player within a chunk, and the location of the chunk within the world. In reduced mode, only the location within the chunk is displayed.
Facing	The direction in which a player is facing. Toward Positive X/Z indicates the player's alignment toward the x/z axis. The two numbers at the end indicate the player's horizontal (azimuthal) and vertical (altitudinal) rotation.
Client Light	The client-side light values, where a is the sky light level and b is the block light level. The first number is the total light level where the player's feet are. Note that there are a few caveats here due to the sky light level showing the light level the block would get from the sun in full daylight, but does not account for the lower light levels at night or during a storm. The second number is the amount of light from the sky at the block the player's feet are in. Same caveat as above. The third number is the amount of light from other blocks (e.g. torches) at the block the player's feet are in.
Server Light	The server-side light values. Exactly the same as the described in Client Light, but the first number "total light level" doesn't exist.
CH	Describes the Y coordinate of the highest block that exists at the player's current X/Z coordinates, client side. CH: client-side values S: The Y coordinate of the highest non-air block at this X/Z coordinate. M: The Y coordinate of the highest block at this X/Z coordinate that has a blocking-motion material or is liquid.
SH	Describes the Y coordinate of highest block that exists at the player's current X/Z coordinates, server side. SH: server-side values S: The Y coordinate of the highest non-air block at this X/Z coordinate. O: The Y coordinate of the highest block at this X/Z coordinate that has a blocking-motion material. M: The Y coordinate of the highest block at this X/Z coordinate that has a blocking-motion material or is liquid. ML: The Y coordinate of the highest block at this X/Z coordinate that has a blocking-motion material and is not leaves.
Biome	Shows the player what biome they are in.
Local Difficulty	Shows the difficulty of the chunk the player is in. See Difficulty on how this works. The second number in parentheses always is 0 since a bug.
Looking at block	Shows the coordinates of the block the player is looking at. If the player is not looking at any block, this entry does not appear.
Looking at liquid	Shows the coordinates of the liquid the player is looking at. If the player is not looking at any liquid, this entry still appears, however, the player has to be looking at a block, and it will display that block's coordinate.
Sounds	Represented by: Number of sounds playing/maximum of sounds playing. The first pair represents sounds as breaking or placing a block, moving or burning fire. The second pair represents ambient (and loopTemplate:Verify) sounds. The mood in parentheses indicates how close the player is to the next cave sound (20w12a+).
Debug*	Tells the player whether the debug pie, or the FPS + TPS graphs are visible or not.
For help*	Tells the player to press F3 + Q for extra debug stuff, see below for more info.

Right side[edit | edit source]

Name	Description
Java*	Tells what Java version the player is running and if it is 32 or 64bit.
Mem*	The amount of memory that the game uses (as a percent as well), over the max amount of memory the game can use.
Allocated*	The amount of memory the game has allocated from the max the game can use, also as a percent.
CPU*	The CPU, including how many threads it has, what brand and it's exact model and at what speed the CPU runs (in GHz) that the player uses
Display*	The resolution of Minecraft (as well as what the name of the GPU company), The graphics card, the OpenGL version and what driver the player uses.
Targeted Block	Displays exactly what block the player is targetting, the block's blockstates and what tags it has. Only shows when the player is looking at a block.
Targeted Fluid	Displays exactly what fluid the player is targetting, the fluid's blockstates and what tags it has. Only shows when the player is looking at a block or fluid. If the player is targetting to a non-fluid block, displays "minecraft:empty" instead.
Targeted Entity	Displays exactly what entity the player is targetting, nothing else. Only shows when the player is looking at an entity.

Profiler graph[edit | edit source]

Pie charts in the lower right of the Shift+F3 debug screen display real-time profiling information. More detailed information about one section can be displayed by using the keys 1-9. Press 0 to go back to the previous section.

File:Debug Pie Chart.png

Screenshot of the debug pie chart in Java Edition 1.15.2.

Frame time graph[edit | edit source]

Bar chart in the lower left of the Alt+F3 debug screen displays real time measurement of seconds per frame with lines marking ¹⁄₆₀ and ¹⁄₃₀ seconds per frame. The graph is color coded from green to yellow to red, with green being faster frame time, red being slower frame time, and yellow in between. The graph also provides ticks per frame with a line marking ¹⁄₂₀ ticks per frame. The color is the exact same as the FPS graph.

File:TPS & FPS Graph.png

Screenshot of the frame time graph in Java Edition 1.15.2.

More debug-keys[edit | edit source]

Text appears in chat for most debug keys listed here. Note that when using a specific key combination like F3+N, F3+B, etc., the debug screen does not open.

F3+A : Reload all chunks.
F3+B : Toggle visibility of hitboxes of visible entities. It also shows which direction entities are looking, as well as the entities eye level.
F3+C : Copies the player's coordinates and rotation in the form of a Template:Cmd command.
- Holding for 10 seconds instead forces a debug crash.
- Control+F3+C forces a Java crash instead of a regular Minecraft crash. However, with some keyboards, it triggers only with right control, thus using left control produces a regular crash.^[3]

File:F3-C Crash Alert.PNG

Screenshot of the crash alert given in the chat while holding F3+C.

F3+D : Clear chat history (including previously typed messages and commands) (As of Java Edition 1.15.2, players can still use the up button to view previous commands/things they said in chat).
F3+F : Increases render distance by 1 (must be between 2 and 32).
F3+shift+F : Decreases render distance by 1 (must be between 2 and 32).
F3+G : Toggles the visible chunk borders around the player.
F3+H : Toggle visibility IDs of items, durability of tools, armor color. and the scale of maps when such items in an inventory.
F3+I : Copies block or entity data to the clipboard.
F3+N : Cycle between Creative and Spectator gamemodes.
F3+P : Toggle automatic pause when Minecraft loses focus on / off.
F3+Q : Gives help and shows all F3 + key combinations.
F3+T : Reload textures, models, sounds, and any other resource pack contents.
F3+Esc : Toggle pause without pause menu (if pausing is possible).
shift+F3 : Opens the debug screen with the profiler graph.
Alt+F3 : Opens the debug screen with the Frame time graph.
(note that both graphs can be opened with shift+Alt+F3)

When the reducedDebugInfo gamerule is set to true, the effects of F3+B (entity hitboxes), F3+G (chunk boundaries), F3+C (copying coordinates), and F3+I (copying block/entity data) are not shown. Holding down F3+C to initiate a crash still works as expected, as well as Control+F3+C

History[edit | edit source]

File:DebugScreenAlpha.png

The debug information from Indev, Infdev, and early Alpha.

youarecrazyright youarecrazyright youarecrazyright youarecrazyright youarecrazyright youarecrazyright youarecrazyright youarecrazyright youarecrazyright youarecrazyright youarecrazyright youarecrazyright youarecrazyright youarecrazyright youarecrazyright youarecrazyright youarecrazyright youarecrazyright youarecrazyright youarecrazyright youarecrazyright youarecrazyright youarecrazyright youarecrazyright youarecrazyright youarecrazyright youarecrazyright youarecrazyright youarecrazyright youarecrazyright youarecrazyright youarecrazyright youarecrazyright youarecrazyright youarecrazyright youarecrazyright youarecrazyright youarecrazyright youarecrazyright youarecrazyright youarecrazyright youarecrazyright youarecrazyright youarecrazyright youarecrazyright youarecrazyright

Pre-1.8 legend[edit | edit source]

Name	Description^[4]^[5]
C	Number of chunk sections rendered over total number of chunks. Counts all render passes: if a chunk section is rendered twice (because it contains both water and normal blocks, for example) then it is counted twice.
F	Number of chunk sections loaded outside the viewing distance. Counts all render passes.
O	Number of chunk sections removed through occlusion culling. Counts all render passes.
E (first row)	Number of empty chunk sections. These sections are skipped for one of two reasons: Either the chunk has not yet been loaded and rendered into polygons, or the section has nothing to draw in the current render pass. Counts all render passes.
E (second row)	Number of rendered entities over total entities
B	Unused, always 0.
I	Number of invisible entities
P	Number of particles on screen
T	Displays the player's max framerate
ALL	Displays the total number of loaded entities (including mobs and dropped items)
ServerChunkCache ChunkCache	The most chunks that can be loaded
x	Player's location in blocks East of 0,0 (negative values are to the West) and after the // is the player's chunk number with the block within the chunk in ()
y	Player's altitude in blocks (63 (62.9) is overworld sea level, 11 (10.9) is overworld lava flood level, 32 (31.9) is nether lava sea).
z	Player's location in blocks South of 0,0 (negative values are to the North) and after the // is the player's chunk number with the block within the chunk in ()
f	The direction in which a player is facing (south=0, west=1, north=2, east=3) and if the player walks toward x or z respectively
lc	Max section height for the chunk the player is in (uses cubic chunk sections, so heights display in multiples of 16 minus 1).
b	Shows the player what biome they are in.
bl	(for "block light") The amount of light from other blocks (e.g. torches) at the block the player's head is in. If the player stands on top of a torch, this field shows a light level of 13 instead of the expected 14, due to the player's head being one block away from it.
sl	(for sky light) The amount of light from the sky at the block the player's head is in. Note that the number shown here is accurate only during the day. It shows the light level the block would get from the sun in full daylight, but does not account for the lower light levels at night or during a storm.
rl	(for raw light) The total light level where the player's head is, equal to max (bl,sl). Note that because the "sl" field is factored in here, this field has the same caveats as that one.
ws	Walking speed.
fs	Flying speed.
g	On ground, Boolean value, true if the player touches the ground.
fl	The y-coordinate of the highest block where the player is able to stand, rounded up when standing on half-blocks, such as slabs. When above the void (where there is no block), it equals 0.
shader	The file path of the currently-active shader (within the "assets" directory of minecraft.jar). Displayed only if a shader is active.

Trivia[edit | edit source]

Biome, and the lighting values do not display when the player are in the void or above y = 255.
When used in a chunk that was created prior to Alpha 1.2 (when there were no biomes), the B field reads "Ocean".
Deeper into the profiler (Shift+F3), some tasks have numbers higher than 9 and can't be accessed. Pressing the two keys simultaneously does not open the task.

Issues[edit | edit source]

Template:Issue list

Gallery[edit | edit source]

Debug Screen Performance Profiler Sneak Peek.png

A sneak peek of the performance profiler shown on Notch's Twitter on October 2, 2011^[6]
Chunk borders.png

Showing the chunk borders debug feature
Hitboxes.png

Showing the hitboxes debug feature