Getting Blender Models Into Roblox at the Right Scale: Studs, Avatar Proportions, and Reference Dummies

Have you ever imported a doorway from Blender, dropped an avatar beside it in Studio, and found a frame that either towers over the character or is so tight your NPCs refuse to path through it? If you build environments for Roblox, you will run into this sooner or later.

Scale problems rarely come from bad modeling. They come from three systems — Blender's unit settings, the FBX exporter, and Studio's 3D Importer — that each make a reasonable assumption about what one unit means, and by default those assumptions often disagree.

This guide covers the conversion math, the Blender settings that keep it predictable, and a reference-dummy workflow that catches sizing mistakes before export instead of after. Our concierge desk works through this same pipeline with creators, and the steps below hold up across single props, modular kits, and full environments.

What Is A Stud In Real-World Terms?

Every size decision in Roblox comes back to the stud, so it is worth pinning down what the unit means before you open Blender. Roblox documents one stud as 0.28 meters for its unit conversions.

At that ratio, a 2-meter wall comes in at about 7.1 studs and a 10-meter building at about 35.7 studs. Movement is measured in studs too: the default WalkSpeed of 16 studs per second works out to roughly 4.5 meters per second, so a 100-stud hallway takes a little over six seconds to cross.

That said, the conversion only gets you halfway. Roblox avatars are stylized, so a default blocky R15 character at about 5 studs works out to roughly 1.4 meters, while an average adult is closer to 1.75 meters, or about 6.25 studs.

This is why a strict real-world conversion tends to make spaces feel slightly oversized for blocky avatars and slightly cramped for taller Rthro bodies. Keep in mind that the goal is playable scale, not architectural accuracy.

Setting Up Blender's Unit System For Roblox

Blender defaults to the Metric system with a Unit Scale of 1.0, which means one grid unit equals one meter. There are two workable options from there, and the right one depends mostly on whether your reference material comes in real-world measurements or in studs.

Here is how the two workflows compare:

We recommend the stud-native workflow for most Roblox projects. After all, nearly every gameplay number you tune later — WalkSpeed, jump height, part sizes, raycast distances — is in studs, and modeling in the same unit takes a conversion step out of every conversation between artists and scripters.

To set it up, open the Scene Properties tab, expand Units, and set Unit System to None. Next, leave the viewport overlay's grid Scale at 1.0 and turn on Snap to Increment so blockout geometry lands on whole studs.

Remember that changing Unit System does not resize anything already in the scene. If you switch partway through a project, check existing assets with the N-panel Dimensions readout before you assume they match.

Building A Reference Scene With R15 Dummies

A number in a spreadsheet is easy to misread, but a character standing in a doorway is hard to miss. The most reliable scale check is a Blender reference scene that contains the same rigs your players will use.

Here's a list of the steps to build one:

1. Insert rigs in Studio. Open the Avatar tab, launch Rig Builder, and insert an R15 Block Rig, an Rthro rig, and an Rthro Slender rig side by side. Space them a few studs apart so their silhouettes do not overlap.
2. Export the selection. Select all three rigs, right-click, and choose Export Selection to save an OBJ file. Name it with the date so you can tell when the reference was captured.
3. Import into Blender. Import the OBJ into a dedicated collection named something like REF_Avatars. Confirm that the block rig reads about 5 units tall in the N-panel.
4. Lock the collection. Disable selection and rendering on the collection. The dummies stay visible as guides but can never leak into an export.

If the imported block rig reads about 0.05 or 500 units tall instead of about 5, the OBJ came through with a unit mismatch. Rescale the collection until the block rig measures 5 units and note the factor — that is the conversion between Studio's exporter and your Blender scene.

Moreover, Studio's avatar settings let you restrict or allow body scaling. Test against the tallest and widest body type your experience permits, not only the default block rig.

Once the collection is set up, save it into your Blender startup file or a linked library file. That way, every new scene opens with the reference dummies already in place.

How Big Should Doors, Props, And Environments Be?

Roblox does not publish an official architecture standard, so the targets below are working conventions. They are sized to clear the reference rigs, leave room for the default third-person camera, and keep PathfindingService agents moving, so treat them as starting points to check against your own dummies.

Some common working targets include:

Doors need the most attention because they can fail in two directions at once. A standard real-world door of 0.9 by 2.0 meters converts to about 3.2 by 7.1 studs — tall enough for a block rig, but narrower than the 4-stud gap PathfindingService needs at its default AgentRadius of 2.

As a result, NPCs that walk fine across open terrain can stall at every interior threshold. Our guide to Roblox NPC pathfinding covers the agent parameters that interact with these dimensions, and our breakdown of procedural room generation in Roblox shows how to build door sizes into a modular kit so every generated room inherits them.

Props follow the same logic at a smaller scale. For instance, handheld tools usually work best between 1 and 4 studs long, which reads clearly in the character's grip without clipping through the torso during animations.

Finally, environments need extra room for the camera. Because the default camera orbits behind the character, tight corridors and low ceilings make it pop and clip, and players read that as poor level design even when the geometry is technically correct.

Plan room sizes alongside your lighting. Lighting zones in Roblox work best when rooms are sized consistently enough that one zone's settings carry across a whole wing.

Exporting From Blender Without Losing Scale

Even a correctly scaled model can arrive in Studio at the wrong size if its object transforms are not clean. Before exporting, work through the following checks:

• Apply transforms. Select the object, press Ctrl+A, and apply Rotation and Scale so the N-panel reads 1.0 scale and 0° rotation. Unapplied scale often causes a mesh to arrive at the wrong size or with inverted normals.
• Set the origin deliberately. Put the origin at the base center for props and doors so the mesh sits flush when you position it in Studio. For modular wall pieces, put it at a corner that lines up with your snap grid.
• Match the axes. Blender is Z-up and Roblox is Y-up, so export FBX with Forward set to -Z and Up set to Y. Check the importer preview to confirm the mesh is standing upright and not lying on its back.
• Keep the scale field at 1.0. Leave the FBX exporter's Scale at 1.00 and let the importer's File Dimensions setting handle conversion. Adding a manual export scale on top of an importer conversion is how a 5-stud door turns into a 500-stud door.
• Export selected objects only. Turn on Limit to Selected Objects so reference dummies, lights, and cameras stay out of the file. This also keeps file sizes small for faster import.

All of these settings can be saved as an FBX operator preset in Blender. Give it a name like Roblox_Studs so everyone on the team exports the same way.

Keep in mind that Blender's FBX exporter writes its own unit metadata into the file. That metadata is the reason the calibration step in the next section matters.

Importing Into Studio And Verifying Scale

Studio's 3D Importer reads the FBX, shows a preview, and exposes settings that control how the file's units become studs. The most important one is File Dimensions, which tells Studio what unit the source file should be read in.

The calibration cube is the most valuable habit in this workflow. Create a 1 × 1 × 1 cube in Blender, export it with your preset, import it with your chosen File Dimensions, and read the MeshPart's Size in the Properties window.

If the cube arrives at 1 × 1 × 1, every other asset exported the same way will arrive at the size you modeled. If it arrives at 100 × 100 × 100 or 0.01 × 0.01 × 0.01, the exporter and importer disagree about centimeters versus meters — change File Dimensions, not your models.

Once the pipeline is calibrated, check real assets against the reference rigs in Studio. Insert the same Rig Builder dummies you exported earlier, place them beside each door and prop, and walk a test character through every threshold in Play mode.

For larger projects, you can automate part of this check from the command bar or a test script. Assuming your doors are grouped in a Doors folder and their width runs along the X axis, a short Luau loop flags any door mesh narrower than 4 studs:

for _, door in workspace.Doors:GetChildren() do
	if door:IsA("MeshPart") and door.Size.X < 4 then
		warn(door.Name, "is only", door.Size.X, "studs wide")
	end
end

Checks like this fit naturally into an automated suite. Our guide to unit testing in Roblox shows how to run them on every build, and Luau type checking keeps the helper functions reliable as your asset list grows.

Common Scale Failures And What Causes Them

Most scale problems come from a handful of causes, and each has a direct fix. The failures to watch for include:

• Mesh arrives 100 times too large or too small. The exporter wrote centimeters and the importer read studs, or the reverse. Re-run the calibration cube and change File Dimensions until the cube measures 1 stud.
• Mesh arrives at the right size but rotated. The axis settings were left at the exporter's defaults. Apply rotation first, then re-export with Forward -Z and Up Y.
• Modular pieces leave hairline gaps. Origins or dimensions drifted off the stud grid. Snap vertices to whole or half-stud increments and keep origins on grid corners.
• Doors fit players but block NPCs. The opening was sized from real-world references. Widen it to at least 4 studs to clear the default pathfinding agent.
• Mesh exceeds Studio's import limits. Large environment meshes can exceed the per-mesh triangle budget or the 2,048-stud maximum MeshPart size on any axis. Split them into modular sections in Blender before export.

Every one of these failures is cheaper to catch in Blender than in Studio. A minute spent checking against the reference dummies saves a re-export, a re-upload, and a round of collision fixes.

Build The Pipeline Once

Scale is decided once for the whole pipeline, not separately for each asset. Choose stud-native or real-world meters, save the FBX preset, keep the R15 reference collection in your Blender startup file, and re-run the calibration cube whenever Studio or Blender ships an update.