diff --git a/source/engine/import/importerbim.js b/source/engine/import/importerbim.js
index 3fa3762..69d26fb 100644
--- a/source/engine/import/importerbim.js
+++ b/source/engine/import/importerbim.js
@@ -11,6 +11,7 @@ import { Matrix } from '../geometry/matrix.js';
 import { Transformation } from '../geometry/transformation.js';
 import { ColorToMaterialConverter } from './importerutils.js';
 import { Property, PropertyGroup, PropertyType } from '../model/property.js';
+import { Unit } from '../model/unit.js';
 
 export class ImporterBim extends ImporterBase
 {
@@ -43,6 +44,8 @@ export class ImporterBim extends ImporterBase
 
     ImportContent (fileContent, onFinish)
     {
+        this.model.SetUnit (Unit.Meter);
+
         let textContent = ArrayBufferToUtf8String (fileContent);
         let bimJson = null;
         try {
diff --git a/source/engine/import/importerocct.js b/source/engine/import/importerocct.js
index f47c919..991c401 100644
--- a/source/engine/import/importerocct.js
+++ b/source/engine/import/importerocct.js
@@ -5,6 +5,7 @@ import { RGBColorFromFloatComponents } from '../model/color.js';
 import { ConvertThreeGeometryToMesh } from '../threejs/threeutils.js';
 import { ImporterBase } from './importerbase.js';
 import { ColorToMaterialConverter } from './importerutils.js';
+import { Unit } from '../model/unit.js';
 
 export class ImporterOcct extends ImporterBase
 {
@@ -61,6 +62,10 @@ export class ImporterOcct extends ImporterBase
             return;
         }
 
+        if (format === 'step' || format === 'iges') {
+            this.model.SetUnit (Unit.Millimeter);
+        }
+
         let fileBuffer = new Uint8Array (fileContent);
         this.worker.postMessage ({
             format : format,
diff --git a/source/engine/main.js b/source/engine/main.js
index f0c05c9..ffd2082 100644
--- a/source/engine/main.js
+++ b/source/engine/main.js
@@ -60,6 +60,7 @@ import { Property, PropertyGroup, PropertyToString, PropertyType } from './model
 import { GetTriangleArea, GetTetrahedronSignedVolume, CalculateVolume, CalculateSurfaceArea } from './model/quantities.js';
 import { TopologyVertex, TopologyEdge, TopologyTriangleEdge, TopologyTriangle, Topology } from './model/topology.js';
 import { Triangle } from './model/triangle.js';
+import { Unit } from './model/unit.js';
 import { ParameterListBuilder, ParameterListParser, CreateUrlBuilder, CreateUrlParser, CreateModelUrlParameters, ParameterConverter } from './parameters/parameterlist.js';
 import { ModelToThreeConversionParams, ModelToThreeConversionOutput, ThreeConversionStateHandler, ThreeNodeTree, ConvertModelToThreeObject } from './threejs/threeconverter.js';
 import { ThreeModelLoader } from './threejs/threemodelloader.js';
@@ -270,6 +271,7 @@ export {
     TopologyTriangle,
     Topology,
     Triangle,
+    Unit,
     ParameterListBuilder,
     ParameterListParser,
     CreateUrlBuilder,
diff --git a/source/engine/model/model.js b/source/engine/model/model.js
index 464b01b..562757c 100644
--- a/source/engine/model/model.js
+++ b/source/engine/model/model.js
@@ -1,17 +1,29 @@
 import { MeshInstance, MeshInstanceId } from './meshinstance.js';
 import { Node } from './node.js';
 import { ModelObject3D } from './object.js';
+import { Unit } from './unit.js';
 
 export class Model extends ModelObject3D
 {
     constructor ()
     {
         super ();
+        this.unit = Unit.Unknown;
         this.root = new Node ();
         this.materials = [];
         this.meshes = [];
     }
 
+    GetUnit ()
+    {
+        return this.unit;
+    }
+
+    SetUnit (unit)
+    {
+        this.unit = unit;
+    }
+
     GetRootNode ()
     {
         return this.root;
diff --git a/source/engine/model/unit.js b/source/engine/model/unit.js
new file mode 100644
index 0000000..a1384a1
--- /dev/null
+++ b/source/engine/model/unit.js
@@ -0,0 +1,9 @@
+export const Unit =
+{
+    Unknown : 0,
+    Millimeter : 1,
+    Centimeter : 2,
+    Meter : 3,
+    Inch : 4,
+    Foot : 5
+};
diff --git a/source/website/sidebar.js b/source/website/sidebar.js
index 04e304a..1cfea2a 100644
--- a/source/website/sidebar.js
+++ b/source/website/sidebar.js
@@ -97,9 +97,9 @@ export class Sidebar
         this.panelSet.Clear ();
     }
 
-    AddObject3DProperties (object3D)
+    AddObject3DProperties (model, object3D)
     {
-        this.detailsPanel.AddObject3DProperties (object3D);
+        this.detailsPanel.AddObject3DProperties (model, object3D);
     }
 
     AddMaterialProperties (material)
diff --git a/source/website/sidebardetailspanel.js b/source/website/sidebardetailspanel.js
index af4b767..cc998c8 100644
--- a/source/website/sidebardetailspanel.js
+++ b/source/website/sidebardetailspanel.js
@@ -9,6 +9,24 @@ import { CreateInlineColorCircle } from './utils.js';
 import { GetFileName, IsUrl } from '../engine/io/fileutils.js';
 import { MaterialType } from '../engine/model/material.js';
 import { RGBColorToHexString } from '../engine/model/color.js';
+import { Unit } from '../engine/model/unit.js';
+
+function UnitToString (unit)
+{
+    switch (unit) {
+        case Unit.Millimeter:
+            return 'Millimeter';
+        case Unit.Centimeter:
+            return 'Centimeter';
+        case Unit.Meter:
+            return 'Meter';
+        case Unit.Inch:
+            return 'Inch';
+        case Unit.Foot:
+            return 'Foot';
+    }
+    return 'Unknown';
+}
 
 export class SidebarDetailsPanel extends SidebarPanel
 {
@@ -27,14 +45,18 @@ export class SidebarDetailsPanel extends SidebarPanel
         return 'details';
     }
 
-    AddObject3DProperties (object3D)
+    AddObject3DProperties (model, object3D)
     {
         this.Clear ();
         let table = AddDiv (this.contentDiv, 'ov_property_table');
         let boundingBox = GetBoundingBox (object3D);
         let size = SubCoord3D (boundingBox.max, boundingBox.min);
+        let unit = model.GetUnit ();
         this.AddProperty (table, new Property (PropertyType.Integer, 'Vertices', object3D.VertexCount ()));
         this.AddProperty (table, new Property (PropertyType.Integer, 'Triangles', object3D.TriangleCount ()));
+        if (unit !== Unit.Unknown) {
+            this.AddProperty (table, new Property (PropertyType.Text, 'Unit', UnitToString (unit)));
+        }
         this.AddProperty (table, new Property (PropertyType.Number, 'Size X', size.x));
         this.AddProperty (table, new Property (PropertyType.Number, 'Size Y', size.y));
         this.AddProperty (table, new Property (PropertyType.Number, 'Size Z', size.z));
diff --git a/source/website/website.js b/source/website/website.js
index 50f4cb3..50677a8 100644
--- a/source/website/website.js
+++ b/source/website/website.js
@@ -900,11 +900,11 @@ export class Website
                 this.UpdateMeshesSelection ();
             },
             onSelectionCleared : () => {
-                this.sidebar.AddObject3DProperties (this.model);
+                this.sidebar.AddObject3DProperties (this.model, this.model);
             },
             onMeshSelected : (meshInstanceId) => {
                 let meshInstance = this.model.GetMeshInstance (meshInstanceId);
-                this.sidebar.AddObject3DProperties (meshInstance);
+                this.sidebar.AddObject3DProperties (this.model, meshInstance);
             },
             onMaterialSelected : (materialIndex) => {
                 this.sidebar.AddMaterialProperties (this.model.GetMaterial (materialIndex));