Blocks

This article lists the hitboxes (aka bounding boxes) of all blocks in 1.8

Simple Blocks

Block	Widths (b)	Height (b)	Comments
Default	1 × 1	1
Soulsand	1 × 1	0.875
End Portal Frame	1 × 1	0.8125	Eye variant: adds a 0.375 x 0.1875 x 0.375 block on top.
Enchantment Table	1 × 1	0.75
Bed	1 × 1	0.5625	A full bed is composed of two "bed blocks".
Slab	1 × 1	0.5
Daylight Sensor	1 × 1	0.375
Trapdoor	1 × 1	0.1875	Can be flipped to its vertical variant.
Repeater	1 × 1	0.125
Carpet	1 × 1	0.0625
Lilypad	1 × 1	0.015625
Snow Layer	1 × 1	0 0.125 0.25 0.375 0.5 0.625 0.75 0.875	Despite having no height at all (0), A single layer of snow is still tangible.
Anvil	1 × 0.875	1	Centered. Orientable (2 variants).
Piston Base (Powered)	1 × 0.75	1	Centered. Orientable (4 variants).
Wall (3-sided)	1 × 0.75	1	Orientable (4 variants)
Wall (long)	1 × 0.375	1.5	Centered. Orientable (2 variants).
Fencegate	1 × 0.25	1.5	Centered. Orientable (2 variants). Can be flipped to a variant with no hitbox.
Door	1 × 0.1875	1	Orientable (4 variants). Can be flipped to another variant.
Ladder	1 × 0.125	1	Orientable (4 variants).
Pane (long)	1 × 0.125	1	Centered. Orientable (2 variants)/
Chest (long)	0.9375 × 0.875	0.875	Must be next to another chest.
Dragon Egg	0.875 × 0.875	1	Centered. Looks drastically different than its hitbox.
Cactus	0.875 × 0.875	0.9375	Centered. Hurts entities close to it.
Chest	0.875 × 0.875	0.875	Centered.
Cake	0.875 × 0.875 0.875 × 0.75 0.875 × 0.625 0.875 × 0.5 0.875 × 0.375 0.875 × 0.25 0.875 × 0.125	0.5	The full cake is centered. Each bite takes away 0.125b from the West (-X)
...

Composite Blocks

"Except" represents an intangible zone rather than a tangible one.

Block	Widths (b)	Height (b)	Comments
Stair (normal)	Base: 1 × 1 Top: 1 × 0.5	Base: 0.5 Top: 1	Orientable (8 variants)
Stair (convex)	Base: 1 × 1 Top: 0.5 × 0.5	Base: 0.5 Top: 1	Orientable (8 variants). Depends on nearby stairs.
Stair (concave)	Base: 1 × 1 Except: -0.5 × -0.5	Base: 1 Except: -0.5	Orientable (8 variants) Depends on nearby stairs
End Portal Frame (eye)	Base: 1 × 1 Eye: 0.375 × 0.375	Base: 0.8125 Eye: 1	The eye looks bigger than it is. It appears 8 px in width, but is actually 6 px wide
Cauldron	Base: 1 × 1 Except: -0.75 × -0.75	Base: 1 Except: -0.6875
Brewing Stand	Base: 1 × 1 Rod: 0.125 × 0.125	Base: 0.125 Rod: 0.875	The base looks smaller than it is. It appears 14 px in width, but is actually 16 px wide.
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Other

Block	Widths (b)	Height (b)	Comments
Boat	1.5 x 1.5	0.6	Entity.