diff --git a/src/ifcopenshell-python/ifcopenshell/util/unit.py b/src/ifcopenshell-python/ifcopenshell/util/unit.py
index dfadebe5f1..89e4466b6c 100644
--- a/src/ifcopenshell-python/ifcopenshell/util/unit.py
+++ b/src/ifcopenshell-python/ifcopenshell/util/unit.py
@@ -912,6 +912,13 @@ def convert_file_length_units(ifc_file: ifcopenshell.file, target_units: str = "
             new_value = convert_value(val)
             setattr(element, attr.name(), new_value)
 
+    # IfcGeometricRepresentationContext.Precision is typed as a plain IfcReal
+    # but is interpreted in the project length unit, so it must be scaled too.
+    # Subcontexts derive Precision from their parent and cannot be set.
+    for context in file_patched.by_type("IfcGeometricRepresentationContext", include_subtypes=False):
+        if context.Precision is not None:
+            context.Precision = convert_unit(context.Precision, old_length, new_length)
+
     has_map_unit = False
     if (
         ifc_file.schema == "IFC2X3"
diff --git a/src/ifcopenshell-python/test/util/test_unit.py b/src/ifcopenshell-python/test/util/test_unit.py
index 17f7fd9976..38d78ba024 100644
--- a/src/ifcopenshell-python/test/util/test_unit.py
+++ b/src/ifcopenshell-python/test/util/test_unit.py
@@ -19,6 +19,7 @@
 from math import pi
 
 import numpy as np
+import pytest
 
 import ifcopenshell.api.context
 import ifcopenshell.api.georeference
@@ -258,6 +259,23 @@ class TestConvertFileLengthUnits(test.bootstrap.IFC2X3):
         assert max(i.id() for i in output) == len(output.wrapped_data.entity_names()) + 1
         assert subject.get_full_unit_name(subject.get_project_unit(output, "LENGTHUNIT")) == "METRE"
 
+    def test_precision_conversion(self):
+        # Regression test for #6127: IfcGeometricRepresentationContext.Precision
+        # is typed IfcReal but interpreted in the project length unit, so it must
+        # be scaled along with the length measures.
+        ifcopenshell.api.root.create_entity(self.file, ifc_class="IfcProject")
+        unit = ifcopenshell.api.unit.add_si_unit(self.file, unit_type="LENGTHUNIT", prefix="MILLI")
+        ifcopenshell.api.unit.assign_unit(self.file, units=[unit])
+        context = ifcopenshell.api.context.add_context(self.file, context_type="Model")
+        context.Precision = 0.01
+        # Subcontexts derive Precision from the parent and must be left alone.
+        ifcopenshell.api.context.add_context(
+            self.file, context_type="Model", context_identifier="Body", target_view="MODEL_VIEW", parent=context
+        )
+        output = subject.convert_file_length_units(self.file, target_units="METER")
+        new_context = output.by_type("IfcGeometricRepresentationContext", include_subtypes=False)[0]
+        assert new_context.Precision == pytest.approx(0.00001)
+
     def test_attribute_conversion(self):
         ifcopenshell.api.root.create_entity(self.file, ifc_class="IfcProject")
         unit = ifcopenshell.api.unit.add_si_unit(self.file, unit_type="LENGTHUNIT", prefix="MILLI")