diff --git a/src/Base/UnitsApi.cpp b/src/Base/UnitsApi.cpp
index 3db89f6949..e4eb715d65 100644
--- a/src/Base/UnitsApi.cpp
+++ b/src/Base/UnitsApi.cpp
@@ -163,6 +163,11 @@ bool UnitsApi::isMultiUnitAngle()
     return UserPrefSystem->isMultiUnitAngle();
 }
 
+std::string UnitsApi::getBasicLengthUnit()
+{
+    return UserPrefSystem->getBasicLengthUnit();
+}
+
 // === static translation methods ==========================================
 
 QString UnitsApi::schemaTranslate(const Base::Quantity& quant, double &factor, QString &unitString)
diff --git a/src/Base/UnitsApi.h b/src/Base/UnitsApi.h
index 45099a4f64..b1cd08e57c 100644
--- a/src/Base/UnitsApi.h
+++ b/src/Base/UnitsApi.h
@@ -98,6 +98,9 @@ public:
     //return true if the current user schema uses multiple units for angles (ex. DMS)
     static bool isMultiUnitAngle();
 
+    //return the basic unit of measure for length in the current user schema.
+    static std::string getBasicLengthUnit();
+
     // Python interface
     static PyMethodDef    Methods[];
 
diff --git a/src/Base/UnitsSchema.h b/src/Base/UnitsSchema.h
index bfe5fab95f..e04893772e 100644
--- a/src/Base/UnitsSchema.h
+++ b/src/Base/UnitsSchema.h
@@ -71,6 +71,9 @@ public:
 
     //return true if this schema uses multiple units for angles (ex. DMS)
     virtual bool isMultiUnitAngle() const {return false;}
+
+    //return the basic length unit for this schema
+    virtual std::string getBasicLengthUnit() const { return std::string("mm"); }
 };
 
 
diff --git a/src/Base/UnitsSchemaCentimeters.h b/src/Base/UnitsSchemaCentimeters.h
index ea6ab8e043..b45805233c 100644
--- a/src/Base/UnitsSchemaCentimeters.h
+++ b/src/Base/UnitsSchemaCentimeters.h
@@ -37,6 +37,8 @@ class UnitsSchemaCentimeters: public UnitsSchema
 {
 public:
     QString schemaTranslate(const Base::Quantity& quant, double &factor, QString &unitString) override;
+
+    std::string getBasicLengthUnit() const override { return std::string("cm"); }
 };
 
 } // namespace Base
diff --git a/src/Base/UnitsSchemaImperial1.h b/src/Base/UnitsSchemaImperial1.h
index aaed330630..2360bcc90d 100644
--- a/src/Base/UnitsSchemaImperial1.h
+++ b/src/Base/UnitsSchemaImperial1.h
@@ -41,6 +41,7 @@ public:
     //virtual void setSchemaUnits(void);
     //virtual void resetSchemaUnits(void);
     QString schemaTranslate(const Base::Quantity& quant, double &factor, QString &unitString) override;
+    std::string getBasicLengthUnit() const override { return std::string("in"); }
 };
 
 /** The schema class for the imperial unit system
@@ -53,6 +54,7 @@ public:
     //virtual void setSchemaUnits(void);
     //virtual void resetSchemaUnits(void);
     QString schemaTranslate(const Base::Quantity& quant, double &factor, QString &unitString) override;
+    std::string getBasicLengthUnit() const override { return std::string("in"); }
 };
 
 /** The schema class for the imperial unit system
@@ -65,6 +67,7 @@ public:
     //virtual void setSchemaUnits(void);
     //virtual void resetSchemaUnits(void);
     QString schemaTranslate(const Base::Quantity& quant, double &factor, QString &unitString) override;
+    std::string getBasicLengthUnit() const override { return std::string("ft"); }
 
     //return true if this schema uses multiple units for length (ex. Ft/In)
     bool isMultiUnitLength() const override {return true;}
@@ -81,6 +84,7 @@ public:
     //virtual void setSchemaUnits(void);
     //virtual void resetSchemaUnits(void);
     QString schemaTranslate(const Base::Quantity& quant, double &factor, QString &unitString) override;
+    std::string getBasicLengthUnit() const override { return std::string("ft"); }
 
     //return true if this schema uses multiple units for angles (ex. DMS)
     bool isMultiUnitAngle() const override {return true;}