Comparator Outputs

How it works

Container fullness	Each slot counts as its number of items divided by that item's stack size, so a full slot is 1 and an empty slot is 0. Fullness is the average of all slots.
Formula	The signal is 1 plus 14 times the fullness, rounded down, when the container holds anything, and 0 when it is empty. One item gives 1; only a completely full container gives 15.
Smaller stacks	An item that stacks to 16 counts 4 times as much as one that stacks to 64. One item that does not stack fills its whole slot.
Brewing Stand	It has 5 slots. A potion does not stack, so each potion fills its slot and counts like 64 items in the table.
Double Chest	Both halves are read together as 54 slots, from either half.
Reading through a block	A Comparator reads the block right behind it. If that block gives no reading and is solid, it reads the block behind that one, or an Item Frame on that block facing the same way, whichever is higher.
Music Discs	A Jukebox gives the reading of the disc inside it, playing or not. While a disc plays, the Jukebox also sends a normal signal of 15.

Items needed per signal (items that stack to 64)


1	1	1	1	1	1	1
2	5	14	23	42	124	247
3	10	28	46	83	247	494
4	14	42	69	124	371	741

5	19	55	92	165	494	988
6	23	69	115	206	618	1235
7	28	83	138	247	741	1482
8	32	96	160	288	864	1728

9	37	110	183	330	988	1975
10	42	124	206	371	1111	2222
11	46	138	229	412	1235	2469
12	51	151	252	453	1358	2716

13	55	165	275	494	1482	2963
14	60	179	298	535	1605	3210
15	64	192	320	576	1728	3456

Other blocks with a reading


Cake	14 when whole, 2 less per slice eaten: 14, 12, 10, 8, 6, 4, 2
Candle Cake	14
Cauldron (empty)	0
Water Cauldron, Powder Snow Cauldron	1, 2 or 3 by fill level

Lava Cauldron	3
Composter	0 to 7 by fill level; 8 when Bone Meal is ready
End Portal Frame	15 with an Eye of Ender, 0 without
Item Frame, Glow Item Frame	0 when empty; 1 as placed, 1 more for each turn of the item, back to 1 after 8 turns

Jukebox	Depends on the disc (see the Music Disc table); 0 when empty
Lectern	0 without a book; 1 on the first page, rising evenly to 15 on the last page (rounded down). A one-page book gives 15
Respawn Anchor	0, 3, 7, 11, 15 for 0 to 4 charges
Beehive, Bee Nest	Honey level, 0 to 5

Sculk Sensor, Calibrated Sculk Sensor	Frequency of the last vibration (1 to 15) while active, 0 otherwise
Chiseled Bookshelf	Number of the slot last used: top row 1, 2, 3 and bottom row 4, 5, 6, left to right seen from the front; 0 before any use
Shelf (every wood type)	Seen from the front: left slot 1, middle slot 2, right slot 4, added up for the slots holding items (0 to 7). Read from the back only
Crafter	Number of slots that hold an item or are disabled, 0 to 9

Copper Bulb (every oxidation stage, waxed or not)	15 when lit, 0 when off
Copper Golem Statue	1 standing, 2 sitting, 3 running, 4 star pose
Creaking Heart	15 on top of its Creaking, falling by about 1 for every 2 blocks of distance down to 0 at 32 blocks; 0 with no Creaking or when uprooted
Command Block (all three kinds)	Success count of its last command

Detector Rail	While a minecart is on it: the fullness of a minecart with a container, or the success count of a Minecart with Command Block; otherwise 0
Chest, Trapped Chest, Copper Chest, Barrel, Shulker Box, Hopper, Dispenser, Dropper, Furnace, Smoker, Blast Furnace, Brewing Stand, Decorated Pot	Container fullness formula

Music Disc readings


1	C418 - 13
2	C418 - cat
3	C418 - blocks
4	C418 - chirp

5	C418 - far
6	C418 - mall
7	C418 - mellohi
8	C418 - stal, fingerspit - Bounce

9	C418 - strad, Hyper Potions - Lava Chicken
10	Amos Roddy - Tears, C418 - ward
11	C418 - 11, Lena Raine - Creator (Music Box)
12	C418 - wait, Lena Raine - Creator

13	Aaron Cherof - Precipice, Lena Raine - Pigstep
14	Aaron Cherof - Relic, Lena Raine - otherside
15	Samuel Åberg - 5