# Lego brick dimensions

**Lego brick dimensions** are the measurements of Lego bricks. They're essentially all multiples of 1.6 mm units, 5 of which make a single 8 mm *module*, or stud's worth of brick.

### Inner dimensions

Measurement | Units | mm |
---|---|---|

Ceiling | 1 | 1.6 |

Wall | 1 | 1.6 |

Stud height | 1 | 1.6 |

Stud diameter | 3 | 4.8 |

First, let's look at a single brick and plate, examining the dimensions that make up its attributes.

Each wall and ceiling is 1 unit (1.6 mm) thick. The studs themselves are 3 units (4.8 mm) in diameter, and about 1 unit tall, depending on the era.^{[1]}

Each stud's worth of brick or plate is therefore 5 units (8 mm) across, accommodating a stud 3 units in diameter, flanked by up to two walls (of any bricks or plates above it) each 1 unit thick. This length is known as a *module*.

Plates are as short as they can be, consisting of just 1 unit of ceiling on the top, and 1 unit of gap on the bottom, to house the studs of any bricks or plates below.

Bricks are three times this length, consisting of 1 unit of ceiling on the top, and a whopping 5 units of gap on the bottom.

### Outer dimensions

Measurement | Units | mm |
---|---|---|

Module (one stud's worth of length or width) | 5 | 8 |

Plate height | 2 | 3.2 |

Brick height | 6 | 9.6 |

Each brick and plate's length and width is an integral number of modules, as in a multiple of 5 units (8 mm).

More accurately, each brick's length and width has 0.1 mm of wriggle room on each side, so its length and width are (studs × 8 mm) - 0.2 mm. So 7.8 mm, or 15.8 mm, and so on.

Ignoring the studs themselves, each brick's height is a multiple of 6 units (9.6 mm). Plates are a third this height, at 2 units (3.2 mm). Neither have any wriggle room subtracted.

By the late 1970s, this discrepancy between the 6 unit height and 5 unit length would complicate things. It required Technic bricks to be padded with layers of plates in order to connect gears vertically. Similarly, it required designer Erling Dideriksen's headlight brick to be a strange and very specific shape in order to somewhat safely enable sideways building.^{[2]}

## References

- "What are the dimensions of a Lego brick?" R. Schulz,
*Bricks*, Jan 2021 *The Secret Life of Lego Bricks*Daniel Konstanski, 2022, ISBN 978-1-80018-196-0

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