How to Design Perfectly Scaled LEGO MOCs - A Complete Guide to Using the Bobby Brix Scale Converter

Every realistic LEGO MOC starts with the same question: how big should it actually be? Get the scale wrong and even a beautifully built model looks off. Get it right and a handful of bricks can capture the essence of a real ship, building, or vehicle with striking accuracy. The Bobby Brix Scale Converter is the free tool that takes the maths out of the equation entirely.

What Is Scale and Why Does It Matter?

A scale is a ratio that expresses the size relationship between a real-world object and its model counterpart. A 1:1 scale means the model is identical in size to the real thing. As the second number increases, the model gets smaller. A 1:100 scale means the model is 100 times smaller than the original. So 1 cm on the model equals 100 cm (1 metre) in the real world.

For LEGO MOC designers, scale is what separates a model that looks convincing from one that just looks like a pile of bricks. A car built at 1:50 will fit naturally alongside LEGO minifigures. Whereas a battleship built at 1:50 would need to be over six metres long! Choosing the right scale from the start saves you from designing yourself into a corner and saves your wallet from a parts order you weren't prepared for.

The maths behind scale conversion is simple in theory: divide the real measurement by the scale ratio. But when you're juggling width, length, and height across metric and imperial units, and then converting those results into LEGO studs for your digital design software, it gets tedious fast. That's exactly the problem the Bobby Brix Scale Converter solves.

What Is a LEGO Stud?

A LEGO stud is the standard unit of measurement used in LEGO design software like BrickLink Studio 2.0. It corresponds to the width and length of a standard 1×1 LEGO brick which is approximately 8 mm in the real world. When you're designing a MOC digitally, almost every measurement you work with will be expressed in studs, which is why knowing how many studs your model needs to be is one of the first things you need to calculate. Note that studs isn't the only way to measure your model but it is a good reference point between imperial or metric units.

The scale converter outputs your results in both real-world units (centimetres or inches) and LEGO studs simultaneously, so you can take a number straight from the tool and enter it directly into Studio 2.0 without any additional conversion step.

How to Use the Bobby Brix Scale Converter

The Bobby Brix Scale Converter is free to use directly on the store, works on both desktop and mobile, and requires no account or download. Here's how to use it step by step.

A practical example: a Type VIIC U-boat like the U-995 is approximately 67 m / 220 ft long in real life. Enter 6700 cm into the Length field, set the scale to 260, press Convert, and the tool immediately tells you the model needs to be approximately 25.8 cm / 10.1″ long — or about 32 studs.

That's a manageable display model, and it matches the scale used across the Bobby Brix submarine collection.

Choosing the Right Scale for Your MOC

There's no single correct scale for a LEGO MOC, since it depends on what you're building, how large you want the finished model to be, and how much detail you need it to carry. Here's a practical breakdown of the most common scales and what they're best suited for.

• Minifigure Scale (roughly 1:40 to 1:50) is the most popular scale for vehicles, buildings, and environments designed to work alongside LEGO minifigures. At this scale, a minifigure represents an average adult human. It's well-suited for cars, houses, aircraft, and anything you want to be playable or interactive. The tradeoff is size as large subjects like ships or skyscrapers become impractically big at minifigure scale (and expensive if you need to buy new parts).
• Microscale (1:200 to 1:1000 and beyond) is where large objects become manageable. A ship, aircraft carrier, or city block that would be unwieldy at minifigure scale becomes a compact, displayable model at 1:500 or 1:1000. Microscale demands more creative problem-solving. Since you're trying to recreate the silhouette of a subject with fewer bricks rather than replicating every detail, you'll have to make some design sacrifices. This is how the Bobby Brix battleship collection uses a consistent 1:1000 scale, and the submarine collection uses 1:260, keeping all models in the same family visually and allowing them to be displayed together coherently as well.
• Custom scales are perfectly valid too! If none of the standard ratios gives you the dimensions you want, simply try different values in the converter until you find one that produces a model size that works for your space, your parts budget, and your display plans.

The key factors to weigh are: the final size of the model and where you plan to display it; the level of detail you want to achieve; your parts budget; and whether the model will be part of a wider collection that needs to stay consistent in scale. If you're a MOC designer planning to expand your designs into commercial MOC kits, this is very important for branding and keeping a consistent standard of quality across all your models.

Real Scale Examples from the Bobby Brix Collection

Seeing scale in practice is the fastest way to understand it. Here are a few examples from the Bobby Brix MOC catalogue to illustrate how different scales translate into finished model sizes.

The WW2 battleships: Bismarck, Tirpitz, HMS Hood, HMS Nelson and HMS Rodney are all built at 1:1000 scale. The Bismarck in real life is 251 m / 823 ft long. At 1:1000, the model comes out at approximately around 25 cm / 9.8″ in length. Compact enough to sit on a shelf, but large enough to show the ship's distinctive silhouette clearly.

The 1:260 submarine collection: including the ARA San Juan, ARA Santa Cruz, USS Bowfin, and the U-995 Type VII, all use a slightly larger microscale to give the submarines enough length to show their hull proportions convincingly without becoming unwieldy display pieces. Compared to the battleships however, they are displayed in near identical lengths making them perfect to be displayed side by side.

Having a consistent scale within a series isn't just an aesthetic choice. If you do it right, models designed years apart can still be displayed side by side without looking mismatched, and builders who collect multiple designs from the same series always know roughly what size to expect. Choosing the right scale will make your LEGO MOC designs timeless!

Tips for Getting Better Results

• Prototype digitally first. Before committing to buying parts, build your model in BrickLink Studio 2.0 using the stud dimensions the converter gives you. Digital prototyping costs nothing and lets you check whether the scale actually works visually before you spend anything.
• Start small and scale up. If you're new to scaled MOC building, start with a simpler subject at a manageable scale. Design it, assess what works and what doesn't, then apply those lessons to a more ambitious version or a larger scale. Each iteration teaches you something new about how to capture the same detail with different numbers of bricks.
• Try multiple scale ratios. Don't commit to the first number you try. Enter your real-world measurements, try 1:50, then 1:100, then 1:200, and compare the stud counts. The converter recalculates instantly which is something you must use to your advantage.
• Match scales within a series. If your MOC will live alongside other models in a collection, a display, or a series of builds you're sharing online pick a scale and stick to it. Be consistent! Consistency makes a collection look intentional and allows you to compare subjects directly.
• Use real technical drawings. For accurate results, source your real-world measurements from technical drawings, Wikipedia specifications pages, or naval/aviation databases rather than estimating. The converter is only as accurate as the measurements you give it.