1 MMD unit in real world units

1 MMD unit in real world units?

Knowing the real world equivalent of 1 unit can be useful when using 3D software, especially when converting models and animations from one software to another. Here are some examples:

3ds max 1 unit = 1 meter
Bryce 1 unit = 8 feet
Cararra 1 unit = 1 inch
Cinema 4D 1 unit = 1 meter
DAZ Studio 1 unit = 1 centimeter
Hexagon 1 unit = 1 centimeter
Lightwave 1 unit = 1 meter
Maya 1 unit = 1 centimeter
Mirai 1 unit = 1 meter
Modo 1 unit = 1 meter
Poser 1 unit = 8 feet
Silo 1 unit = 10 centimeters
XSI 1 unit = 2.5 centimeters

MikuMikuDance. Strangely, no one seems to know exactly.
1 MMD unit = approximately 8 centimeters.
1 MMD unit = approximately 3 inches.
Hatsune Miku's official height is 158 centimeters (approximately 5 feet, 2 inches)
Miku herself is a little more than 20 MMD units tall.
If we say that Miku is exactly 20 MMD units tall, then:
1 MMD unit = 7.9 centimeters and
1 MMD unit = 3.11 inches

(Each grid square that you see in MikuMikuDance is 5X5 units.)

Blender also does not seem to have any exact value for its units.
The human metarig armature is 1.9347 units tall
If 1 Blender unit = 1 meter, then the human metarig armature would be 1.9347 meters tall
(about 76 inches = 6 feet 4 inches)
If 1 Blender unit = 75 centimeters, then:
The human metarig armature would be 1.451 meters tall
(about 57 inches = 4 feet 9 inches)