Real-World Scale in Blender: Units, Meters and Why Imports Go Wrong

Short answer: Blender works in meters by default, with 1 Blender unit equal to 1 m when Unit Scale is 1.0. Models come in at the wrong size when a file format carries no units (OBJ), when an importer assumes a different unit, or when an object scale was never applied before export. Keep your scene at Metric with Unit Scale 1.0, apply scale before exporting, and a correctly built model arrives at its real size in every format.

This guide is built on a test we ran on October 30, 2026 in Blender on macOS: two delivered models from our Larkspur Farmstead collection, each opened as .blend and imported as FBX, GLB and OBJ, then imported again into a centimeter scene, scaled without applying, exported and measured. The settings named here follow the official Blender manual pages for Scene Properties, FBX and Wavefront OBJ.

How Blender measures size

Everything in Blender is stored in Blender units. The Units panel (Properties > Scene > Units) decides how those units are shown:

• Unit System: None, Metric or Imperial. Metric is the default for a new scene.
• Unit Scale: the factor between internal units and the numbers you see. At 1.0, one Blender unit is one meter.
• Length: the unit used for display, for example Meters or Centimeters.

The Blender manual is explicit that Unit Scale only changes the values displayed in the interface, not how things behave internally; physics simulations, for example, ignore it. That single sentence explains most scale problems. If you set Unit Scale to 0.01 so a 2 m wall reads as 200 cm, the wall is still 2 Blender units long, and anything that reads raw units (a physics solver, an exporter with Apply Unit off, another program) sees 2, not 200.

Our recommendation for anyone who moves models between tools: leave Unit System on Metric, Unit Scale on 1.0 and Length on Meters. If you prefer reading centimeters, change Length to Centimeters and leave Unit Scale alone. The display changes, the data does not.

What we measured: one model, four formats, same size

We tested two pieces with very different shapes. The Oak Two-Door Wardrobe is a floor prop listed at 1.00 by 0.58 by 1.95 m (1,064 triangles), with hinged doors as child objects. The Limestone Wall with Casement Window is a modular wall listed at 2.00 by 0.46 by 3.00 m (270 triangles). We measured the world bounding box of the visible meshes after each step, with default import settings in a fresh metric scene.

All four files land at the size printed on the product page. The 90 degree X rotation on OBJ imports is the importer converting the file's Y-up axis to Blender's Z-up; the model stands upright and keeps its size. That is the baseline you want from any model you buy or build: scale 1, 1, 1 on every object, real-world dimensions in the mesh itself, and every format agreeing.

Why imports go wrong: four causes we reproduced

1. OBJ has no units

An OBJ file stores plain numbers. Whether 2.0 means 2 meters, 2 centimeters or 2 inches is a convention between the exporter and the importer. When we imported the same OBJ with the importer's Scale set to 0.01, as you would for a file assumed to be in centimeters, the 2 m wall came in 2 cm wide and every object carried a scale of 0.01. Nothing in the file could warn us. If an OBJ arrives 100 times too large or too small, the fix is the Scale value in the OBJ import options, not rescaling by eye.

2. Two FBX importers, two answers in a centimeter scene

FBX does record a unit, and what happens to it depends on the importer. We imported the same FBX files into a scene set to Unit Scale 0.01 with Length in Centimeters:

• The built-in importer behind File > Import > FBX placed the wardrobe at 0.998 Blender units wide. In a 0.01 scene that displays as 0.998 cm: a wardrobe the size of a fingernail.
• The older Python importer that ships with the FBX add-on (the one scripts call as import_scene.fbx) set the root empty's scale to 100, so the wardrobe displayed as 99.8 cm, its real size, but with an unapplied scale of 100 on the root.

Neither result is a bug in the file. Both show why a Unit Scale other than 1.0 invites trouble: two tools reading the same data disagree. In a metric scene at 1.0, both importers gave us the real size with a scale of 1.

3. Unapplied object scale travels with the file

We scaled each model's root to 2 in Object Mode without applying it, then exported FBX, GLB and OBJ with default settings and imported them again:

The size is consistent, but FBX and GLB hand the next program an object with a scale of 2. Engines and other tools then multiply that into colliders, child transforms and any script that sets scale, which is where "it looks right but behaves wrong" comes from. After Object > Apply > Scale (Ctrl+A), our models kept their doubled size with every object back at 1, 1, 1. Apply scale before export and the question of how each format stores it goes away.

4. Export settings that rescale on the way out

Blender's FBX exporter has three options that touch size. With our scene at Metric and 1.0, the defaults (Scale 1.00, Apply Unit on, Apply Scalings set to All Local) wrote files that came back at the same size. The tooltips explain the trap: Apply Unit takes the current Blender unit settings into account, and Apply Scalings decides how custom and unit scalings are stored, because Blender uses the FBX scale to detect units on import but many other applications do not. Change one of these to fix a single import and you can break the next one. Fix the scene units and the object scale before you touch export scale.

A checklist before you export

1. Scene > Units: Metric, Unit Scale 1.0. Choose Meters or Centimeters for display under Length.
2. Check real dimensions in the N panel (Item > Dimensions) against something you know: a door is about 2 m tall, a table about 0.75 m.
3. Select the model and apply scale (Ctrl+A > Scale) so every object reads 1, 1, 1. Apply rotation too if your target expects it.
4. Put the pivot where it belongs: bottom center for floor props, the wall's back plane for wall pieces.
5. Export with Scale 1.00. For OBJ, write down that the file is in meters for whoever imports it.
6. Import the exported file into a fresh scene and compare the dimensions before you send it anywhere.

Our own kits follow the same rules, which is why the numbers above match. Every Larkspur model is built in meters with Z up in the .blend, floor props pivot at the bottom center on the ground plane, wall pieces keep their back plane on y = 0, and modular pieces stay on a 2 m building grid so a Limestone Farmhouse Wall (2.00 by 0.41 by 3.00 m) snaps beside the window piece without gaps. Whole buildings such as the Run-Down Starter Cottage (7.40 by 5.74 by 7.25 m) are assembled from those same pieces. Each design in Larkspur Vale ships as BLEND, GLB, FBX and OBJ.

Game engines and meters

Most real-time tools expect one unit to be one meter. The glTF specification states that all linear distances are in meters, so a GLB has no unit setting to get wrong. Unity's import documentation says its physics system expects 1 m in the game world to be 1 unit in the imported file, and its Model import tab offers Scale Factor and Convert Units to correct files that do not match. Those options exist for files built at the wrong scale; a model that already measures right in Blender at scale 1 should not need them. We describe engine options here from their official documentation; our test above covers Blender.

For more on choosing between formats, see our guide to 3D file formats for games. If you are moving models from FBX to OBJ, converting FBX to OBJ in Blender covers textures, pivots and hierarchy. For how modular buildings use a grid, read low poly buildings.

Common questions

What scale does Unity use?

Unity treats 1 unit as 1 meter; its documentation notes that the physics system expects that ratio. A Blender scene at Metric with Unit Scale 1.0 uses the same ratio, so 1 Blender unit equals 1 Unity unit.

Why is my model 100 times too big or too small after import?

Almost always a centimeter and meter mismatch: an OBJ imported with the wrong Scale value, an FBX read by a tool that interprets its unit differently, or a scene with Unit Scale set to 0.01. Start with the scene units, then the import Scale value, then the object scale in the N panel.

Should I apply scale in Blender before exporting?

Yes. In our test an unapplied scale of 2 survived FBX and GLB export as an object scale of 2. Applying it bakes the size into the mesh and leaves every object at 1, 1, 1, which is what engines and other tools handle most predictably.

Is 1 Blender unit 1 meter?

With the default Metric system and Unit Scale 1.0, yes. Changing Unit Scale changes the numbers shown in the interface, not the stored data.