diff --git a/django/template/defaulttags.py b/django/template/defaulttags.py
index c375b5bb1e4..2eee5348303 100644
--- a/django/template/defaulttags.py
+++ b/django/template/defaulttags.py
@@ -402,12 +402,15 @@ class WidthRatioNode(Node):
         try:
             value = self.val_expr.resolve(context)
             maxvalue = self.max_expr.resolve(context)
+            max_width = int(self.max_width.resolve(context))
         except VariableDoesNotExist:
             return ''
+        except ValueError:
+            raise TemplateSyntaxError("widthratio final argument must be an number")
         try:
             value = float(value)
             maxvalue = float(maxvalue)
-            ratio = (value / maxvalue) * int(self.max_width)
+            ratio = (value / maxvalue) * max_width
         except (ValueError, ZeroDivisionError):
             return ''
         return str(int(round(ratio)))
@@ -1143,12 +1146,10 @@ def widthratio(parser, token):
     if len(bits) != 4:
         raise TemplateSyntaxError("widthratio takes three arguments")
     tag, this_value_expr, max_value_expr, max_width = bits
-    try:
-        max_width = int(max_width)
-    except ValueError:
-        raise TemplateSyntaxError("widthratio final argument must be an integer")
+
     return WidthRatioNode(parser.compile_filter(this_value_expr),
-                          parser.compile_filter(max_value_expr), max_width)
+                          parser.compile_filter(max_value_expr),
+                          parser.compile_filter(max_width))
 widthratio = register.tag(widthratio)
 
 #@register.tag
diff --git a/tests/regressiontests/templates/tests.py b/tests/regressiontests/templates/tests.py
index cdd499ec83d..71ca7823848 100644
--- a/tests/regressiontests/templates/tests.py
+++ b/tests/regressiontests/templates/tests.py
@@ -923,7 +923,10 @@ class Templates(unittest.TestCase):
             # Raise exception if we don't have 3 args, last one an integer
             'widthratio08': ('{% widthratio %}', {}, template.TemplateSyntaxError),
             'widthratio09': ('{% widthratio a b %}', {'a':50,'b':100}, template.TemplateSyntaxError),
-            'widthratio10': ('{% widthratio a b 100.0 %}', {'a':50,'b':100}, template.TemplateSyntaxError),
+            'widthratio10': ('{% widthratio a b 100.0 %}', {'a':50,'b':100}, '50'),
+            
+            # #10043: widthratio should allow max_width to be a variable
+            'widthratio11': ('{% widthratio a b c %}', {'a':50,'b':100, 'c': 100}, '50'),
 
             ### WITH TAG ########################################################
             'with01': ('{% with dict.key as key %}{{ key }}{% endwith %}', {'dict': {'key':50}}, '50'),