--- a/eric7/QScintilla/QsciScintillaCompat.py	Tue May 18 19:25:53 2021 +0200
+++ b/eric7/QScintilla/QsciScintillaCompat.py	Wed May 19 17:36:34 2021 +0200
@@ -50,6 +50,19 @@
     
     IndicatorStyleMax = QsciScintilla.INDIC_GRADIENTCENTRE
     
+    # Maps PyQt6.QFont.Weight to the weights used by QScintilla
+    QFontWeightMapping = {
+        100: 0,
+        200: 12,
+        300: 25,
+        400: 50,
+        500: 57,
+        600: 63,
+        700: 75,
+        800: 81,
+        900: 87,
+    }
+    
     def __init__(self, parent=None):
         """
         Constructor
@@ -145,7 +158,7 @@
         
         f = font.family().encode("utf-8")
         ps = font.pointSize()
-        weight = -font.weight()
+        weight = -QsciScintillaCompat.QFontWeightMapping[font.weight()]
         italic = font.italic()
         underline = font.underline()
         bold = font.bold()