What's a Grid Unit

Unlock the power of modular units with our 40mm Grid Unit (GU)

A grid unit, GU for short, is 40mm.

This can be in one dimension - 40mm in length, two dimensions - a 40mm x 40mm square, or in three dimensions - a 40x40x40 cube.

A 40mm x 40mm x 40mm cube representing a grid unit. The cube has two intersecting cylindrical holes drilled through its centre, with each hole having a diameter of 8mm.

Base Units

Modular systems need a base unit that modules reference.

One standard of brick size is 20cm x 10cm.

LEGO has a base unit called the “stud” which is 8mm.

The image shows an isometric view of two LEGO bricks: one red and one yellow. The red brick has two studs on top, and the yellow brick has one stud. Both bricks have the word "LEGO" embossed on their studs. The red brick is rectangular with two circular studs, while the yellow brick is square-shaped with a single circular stud.

Grid Units

Grid Beams

Grid Beams are one application of the Grid Unit.

They are a stack of Grid Unit cubes (pictured above) that make a beam. They are one Grid Unit in width and depth, and the length can be any number of units only limited by the length of the available material.

The 8mm holes of each grid unit cube creates a repeating pattern of holes on 40mm centre along the length of the beam.

The image shows a set of wooden grid beams arranged in ascending order, each representing modular units based on increments of 40mm. The smallest unit is a 40mm cube on the right, and the beams increase in height by 40mm intervals, with the tallest beam on the left reaching 2.4 meters. Each beam features evenly spaced perforations, characteristic of grid beams, allowing for flexible assembly. The background has a grid that visually scales the beams, emphasizing the modular nature of the system. This representation demonstrates the use of 40mm modular units in grid beam construction.

Grid Panels

Grid Panels are another application of Grid Units and one of the essential building blocks of Grid Kit.

Grid Panels are measured in length and width multiples of 40mm and are only limited by the size of the raw material.

An example of a Grid Panel is a sheet of plywood. A standard sheet of plywood is 2400mm x 1200mm or 60gu x 30gu. Each 40mm square of the Grid Panel has an 8mm hole drilled at the centre of the square.

The image shows a grid panel composed of modular units, with each unit measuring 40mm. The panel features a series of perforated holes that are evenly spaced in a grid pattern, likely to allow for flexible attachment or structural support. The grid layout is scaled across the panel, which is labeled with dimensions of 2.4m in height and 1.2m in width. The panel is sectioned into various rectangular shapes, emphasizing the modular nature of the system, where each section corresponds to multiples of 40mm. This design highlights the flexibility of grid-based construction, ideal for various assembly or mounting configurations.

Made With The Grid

With just these two components based on a grid unit, there are many possibilities for what can be built, and the process becomes a simple process of assembly. As more components are developed within the grid unit frame work the complexity of what is possible only increases.

A large bookshelf made from grid beams, filled with vinyl records, books, and a few decorative items. The structure is sturdy, modular, and symmetrical, and the room includes a chair and a record display stand nearby.

A minimalist bed frame made from grid beams with a simple mattress placed on top. The bed is set in a room with large windows that offer a view of hills and buildings outside.

A simple outdoor shelter made from wooden grid beams with hessian (burlap) sheets draped over the structure. Vans are parked nearby, and a decorative structure can be seen in the background with rolling hills under a clear sky.

A close-up of two wooden grid beams connected by a black hinge. Both beams have evenly spaced holes and are securely fastened by screws through the hinge.

A close-up view of a wooden grid beam joint reinforced by an orange triangular bracket. The grid beams are perforated with evenly spaced holes, connected at a 90-degree angle.

Four vertical wooden grid beams with caster wheels attached at the top, ready for mobility. The beams have evenly spaced perforations and are standing upright in front of a textured wall with spray paint marks.

How To Read Grid Units

Grid units remove the need for constant measuring. Components have holes placed at regular intervals, making it easy to count units instead of using a ruler.

Grid Beam Example: A beam labelled 30GU is 30 units long. Multiply the number of units (30) by 40mm to get the length — 1,200mm.
Grid Panel Example: A panel marked 10GU x 25GU is 10 units wide and 25 units long. That equals 400mm x 1,000mm. You can quickly count the holes to confirm the size.

History: Rack Unit

A “rack unit” (or RU or U) is 1.75” (44.45mm) per 1U.

Originally designed for telephone equipment,

A detailed black-and-white technical diagram of a telephone rack system. It shows multiple rows of vertical equipment racks with labeled components such as terminal strips, cable racks, and I-beam panel supports. A rolling ladder is positioned next to the rack, along with a retractable writing shelf. The diagram highlights the complex wiring and structure of the telephone system, including lead-covered cables and local cable formings.

The rack unit is now most commonly used in server racks.

(See also: FutureRack)

And Eurorack modular synthesizers.

A comparative image showing different synthesizer modules organized by size. Each module is displayed side by side, ranging from small 1U tiles to larger 6U Wiard modules. The labels at the bottom specify the types of modular systems: 1U Tile, 2U Mattson Mini, 3U Eurorack, 3u Frac, 4U Serge, 4U Buchla, 5U MOTM, 5U MU Moog, and 6U Wiard. Each module features various knobs, switches, and jacks used in synthesizer setups, with distinct designs that represent different modular formats.

Of course, there's an XKCD comic: #1439

The comic strip shows two characters, one seated at a computer and the other standing nearby, both involved in a humorous conversation. Panel 1: The standing character says, "I've discovered something." The seated character responds with "Oh?" while continuing to work at the computer. Panel 2: The standing character, now shown in close-up, says, "Standard server rack units and standard beehive honeycomb frames are compatible. They're both 19 inches, with similar pitches." The seated character responds with, "Uh oh." Panel 3: The standing character, now gesturing with open arms, says, "I'm pleased to announce that today, for a few hours, Google led the world in datacenter honey production." A beat later, the character adds, "Until their security people kicked me out." Panel 4: The seated character says, "I'm sorry your beekeeping career ended so quickly." The standing character responds, "I'll find a new datacenter. Turns out most colocation TOSs don't mention beehives." The seated character then adds, "I suspect that will soon change."

Why The Grid Unit is 40mm

We chose 40mm because it's compatible with several existing international standards and is a highly composite number.

EuroPallets: 800mm × 1,200mm
Plywood Sheets: 2,400mm × 1,200mm
Aluminum 4040 V-Slot and T-Slot: 40mm × 40mm profiles

Plus, 40mm is a human size measurement. It's simple to imagine holding a 40mm cube, unlike a tiny 1mm cube or a massive 1-meter cube.

What Are Highly Composite Numbers?

Highly composite numbers have more divisors than other numbers of the same size. This means they can be split into many equal parts, making them super useful when you need to divide or organize things evenly.

Why They Work Well

Because they divide evenly without leftovers, highly composite numbers are handy in systems where flexibility is key. You'll find them in timekeeping, scheduling, and data storage.

Everyday Examples

60: Used in time—60 seconds in a minute, 60 minutes in an hour. It divides evenly by 1, 2, 3, 4, 5, 6, 10, 12, 15, 20, and 30. This makes it easy to break time into halves, quarters, sixths, and so on.
12: Shows up in dozens (like eggs or donuts) and 12-hour clocks. It divides evenly by 1, 2, 3, 4, 6, and 12, which helps when splitting things equally.
360: The number of degrees in a circle. It can be divided by many numbers like 2, 3, 4, 5, 6, 8, 9, 10, 12, 15, 18, and more. This is practical for measuring angles and drawing shapes.

International Standards

International standards are global agreements that ensure products work together. By using a 40mm grid unit, Grid Kit is compatible with many existing components and systems, making it easy to integrate with other products already following these standards.