diff --git a/lattice2Base/Rounder.py b/lattice2Base/Rounder.py
index 2baf235..832db2b 100644
--- a/lattice2Base/Rounder.py
+++ b/lattice2Base/Rounder.py
@@ -29,16 +29,66 @@ __doc__ = "helper module for Lattice add-on workbench for FreeCAD. Provides spec
 import math
 from math import log
 
-nice_numbers = [1.0, 2.0, 5.0]
-nice_magnitudes = []
-for degree in range(-3,6):
-    order = 10.0 ** degree
-    nice_magnitudes.extend([order * val for val in nice_numbers])
+# copied from FreeCAD /src/Base/UnitsSchema.h, enum UnitSystem
+class UnitSystem(object): 
+    SI1 = 0 #, /** internal (mm,kg,s) SI system (http://en.wikipedia.org/wiki/International_System_of_Units) */
+    SI2 = 1 #, /** MKS (m,kg,s) SI system */
+    Imperial1 = 2 #, /** the Imperial system (http://en.wikipedia.org/wiki/Imperial_units) */
+    ImperialDecimal = 3 #, /** Imperial with length in inch only */
+    Centimeters = 4 #, /** All lengths in centimeters, areas and volumes in square/cubic meters */
+    ImperialBuilding = 5 #, /** All lengths in feet + inches + fractions */
+    MmMin = 6 #, /** Lengths in mm, Speed in mm/min. Angle in degrees. Useful for small parts & CNC */
     
-def roundToNiceValue(value, nice_value_list = nice_magnitudes):
+    @staticmethod
+    def getActiveSchema():
+        import FreeCAD as App
+        return App.ParamGet("User parameter:BaseApp/Preferences/Units").GetInt("UserSchema", 0)
+
+def getNiceLengths(unitschema = None):
+    if unitschema is None:
+        unitschema = UnitSystem.getActiveSchema()
+    if unitschema == UnitSystem.SI1 or unitschema == UnitSystem.SI2 or unitschema == UnitSystem.Centimeters or unitschema == UnitSystem.MmMin:
+        nice_numbers = [1.0, 2.0, 5.0]
+        nice_magnitudes = []
+        for degree in range(-3,6):
+            order = 10.0 ** degree
+            nice_magnitudes.extend([order * val for val in nice_numbers])
+        return nice_magnitudes
+    elif unitschema == UnitSystem.Imperial1 or unitschema == UnitSystem.ImperialBuilding or unitschema == UnitSystem.ImperialDecimal:
+        inch = 25.4
+        foot = 304.8
+        yard = 914.4
+        mile = 1609344.0
+        #https://forum.freecadweb.org/viewtopic.php?f=8&t=32565#p271923
+        #.005" .010", .025", .050", .100", .250", 1", 6", 1', 8', 50', 100', 500', 1000', 2500', 1 mile, 10 miles, 100 miles
+        return [
+            0.005*inch, 
+            0.010*inch, 0.025*inch, 0.050*inch,
+            0.10*inch, 0.25*inch, 0.50*inch,
+            1*inch, 2*inch, 6*inch,
+            
+            1*foot, 2*foot, 4*foot, 8*foot, 
+            16*foot, 32*foot, 50*foot, 
+            100*foot, 250*foot, 500*foot, 
+            1000*foot, 2500*foot,
+            
+            1*mile, 2*mile, 5*mile, 
+            10*mile, 25*mile, 50*mile, 
+            100*mile
+        ]
+    else:
+        #unit unsupported? fall back to metric
+        import FreeCAD as App
+        App.PrintWarning("Lattice Autosize: Unit schema {n} is not yet supported.\n".format(n= unitschema))
+        return getNiceLengths(UnitSystem.SI1)
+    
+def roundToNiceValue(value, nice_value_list = None):
     if value == 0.0:
         return 0.0
-        
+    
+    if nice_value_list is None:
+        nice_value_list = getNiceLengths()
+    
     bestmatch_logdist = log(1e10)
     bestmatch = None