diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7e2e6cc39..f248685df 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -11,6 +11,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 * Added `list` to accepted types for `Scene.add`.
 * Added `list[float]` to accepted types for `Camera.position` and `Camera.target`.
+* Added `unit` to `Viewer` and `Config`.
 * Added `bounding_box` and `_update_bounding_box` to `BufferObject`.
 
 ### Changed
diff --git a/scripts/unit.py b/scripts/unit.py
new file mode 100644
index 000000000..b262a933f
--- /dev/null
+++ b/scripts/unit.py
@@ -0,0 +1,20 @@
+from compas.colors import Color
+from compas.geometry import Box
+from compas.geometry import Frame
+from compas_viewer.viewer import Viewer
+from compas_viewer.config import Config
+
+config = Config()
+config.unit = "mm"
+viewer = Viewer(config)
+
+for i in range(10):
+    for j in range(10):
+        viewer.scene.add(
+            Box(500, 500, 500, Frame([i * 1000, j * 1000, 0], [1, 0, 0], [0, 1, 0])),
+            show_lines=True,
+            surfacecolor=Color(i / 10, j / 10, 0.0),
+            name=f"Box_{i}_{j}",
+        )
+
+viewer.show()
diff --git a/src/compas_viewer/config.py b/src/compas_viewer/config.py
index fcf5c06ca..3c4da0fc2 100644
--- a/src/compas_viewer/config.py
+++ b/src/compas_viewer/config.py
@@ -369,6 +369,7 @@ class UIConfig(ConfigBase):
 @dataclass
 class Config(ConfigBase):
     vectorsize: float = 0.1
+    unit: Literal["m", "cm", "mm"] = "m"
     ui: UIConfig = field(default_factory=UIConfig)
     window: WindowConfig = field(default_factory=WindowConfig)
     renderer: RendererConfig = field(default_factory=RendererConfig)
diff --git a/src/compas_viewer/viewer.py b/src/compas_viewer/viewer.py
index 04e763550..0c60588ef 100644
--- a/src/compas_viewer/viewer.py
+++ b/src/compas_viewer/viewer.py
@@ -20,12 +20,15 @@
 
 class Viewer(Singleton):
     def __init__(self, config: Optional[Config] = None, **kwargs):
+
+        self.running = False
         self.app = QApplication(sys.argv)
         self.app.setApplicationName("COMPAS Viewer")
         self.app.setApplicationDisplayName("COMPAS Viewer")
         self.app.setWindowIcon(QIcon(os.path.join(HERE, "assets", "icons", "compas_icon_white.png")))
 
         self._scene = None
+        self._unit = "m"
 
         self.config = config or Config()
         self.timer = QTimer()
@@ -36,8 +39,7 @@ def __init__(self, config: Optional[Config] = None, **kwargs):
         # renderer should be part of UI
         self.renderer = Renderer(self)
         self.ui = UI(self)
-
-        self.running = False
+        self.unit = self.config.unit
 
     @property
     def scene(self) -> ViewerScene:
@@ -52,6 +54,31 @@ def scene(self, scene: Scene):
             for obj in self._scene.objects:
                 obj.init()
 
+    @property
+    def unit(self) -> str:
+        return self._unit
+
+    @unit.setter
+    def unit(self, unit: str):
+        if self.running:
+            raise NotImplementedError("Changing the unit after the viewer is running is not yet supported.")
+        if unit != self._unit:
+            previous_scale = self.config.camera.scale
+            if unit == "m":
+                self.config.renderer.gridsize = (10.0, 10, 10.0, 10)
+                self.renderer.camera.scale = 1.0
+            elif unit == "cm":
+                self.config.renderer.gridsize = (1000.0, 10, 1000.0, 10)
+                self.renderer.camera.scale = 100.0
+            elif unit == "mm":
+                self.config.renderer.gridsize = (10000.0, 10, 10000.0, 10)
+                self.renderer.camera.scale = 1000.0
+            else:
+                raise ValueError(f"Invalid unit: {unit}. Valid units are 'm', 'cm', 'mm'.")
+            self.renderer.camera.distance *= self.renderer.camera.scale / previous_scale
+
+        self._unit = unit
+
     def show(self):
         self.running = True
         self.ui.init()