What enables LEGO’s obvious and non-obvious modularity is the deliberate choice of, and adherence to, a prescribed geometric basis – the LEGO Unit (LU). See photos of the dimensioning. As much as possible, the dimensions on each LEGO element are integer-multiples of the LEGO Unit or clean fractions of it. For example, the height of all LEGO studs is 1 LU, the diameter of all studs is 3 LU, the width of 1 x ___ elements is 5 LU, the height of bricks is 6 LU, the height of plates is 2 LU, and so on.

Why is this so important? When it’s time for a LEGO designer to create a new element, like a pile of four ice cream scoops, it’s pretty clear what the diameter of each ice cream scoop should be – 3 LU. Thus, the scoop will naturally fit into anything a LEGO stud could.

Respect for and adherence to the LEGO Unit has given LEGO elements their timelessness and the company its competitive advantage. The first LEGO bricks made in 1958 were consistent with the LEGO Unit, meaning they fit with the bricks made today. As a result, LEGO products rarely show up in a thrift store because they don’t lose their value. They were just as valuable 50 years ago as they will be 50 years from now.

There are thousands of LEGO elements all consistent with the LEGO Unit. Every year the company produces a few new parts, which are added to the family of building elements. Due to their compatibility, the possibilities are much more expansive than their competitors’ who enter the market with only a few hundred building pieces.

Adherence to the LEGO unit puts full creativity into the hands of builders. This authenticity in the building system means builders can think differently than the LEGO element designers to create truly innovative things.

To illustrate what the LEGO Unit has offered to the world’s largest toy company, consider the following.

A few key ratios inherent in the LEGO Unit prove vital in the design of bricks, plates, and other elements upon which the LEGO Group is established. The most utilized and perhaps intuitively understood is 1:3; three plates stacked add to become the height of one brick. This ratio has become so valuable that the ratio itself has become the basis of another unit of measurement known as the “Fundamental LEGO Unit” (FLU). Similarly, we see that a stack of five plates adds to the same height as the length 2x__ elements (as in the same size as the width of a 2x4 brick, for example). Additionally, as the 5:6 width to height ratio is scaled up, we can see applications such as in figure 3.