diff --git a/firka/lib/core/average_helper.dart b/firka/lib/core/average_helper.dart
index 4f04b1a..b255c39 100644
--- a/firka/lib/core/average_helper.dart
+++ b/firka/lib/core/average_helper.dart
@@ -1,10 +1,17 @@
 import 'package:kreta_api/kreta_api.dart';
 
+bool _isPercentageGrade(Grade grade) {
+  final name = grade.valueType.name.toLowerCase();
+  return name.contains('szazalek') || name.contains('percent');
+}
+
 double calculateAverage(List<Grade> sortedGrades) {
   double totalWeight = 0.0;
   double weightedSum = 0.0;
 
   for (final grade in sortedGrades) {
+    if (_isPercentageGrade(grade)) continue;
+
     final value = grade.numericValue;
     final weight = grade.weightPercentage;
 
diff --git a/firka/lib/data/widget.dart b/firka/lib/data/widget.dart
index ae4e347..20dbe03 100644
--- a/firka/lib/data/widget.dart
+++ b/firka/lib/data/widget.dart
@@ -322,6 +322,11 @@ class WidgetCacheHelper {
     var sum = 0.0;
 
     for (var grade in grades) {
+      final name = grade.valueType.name.toLowerCase();
+      final isPercentage =
+          name.contains('szazalek') || name.contains('percent');
+      if (isPercentage) continue;
+
       if (grade.numericValue != null) {
         var weight = (grade.weightPercentage ?? 100) / 100.0;
         weightTotal += weight;
diff --git a/firka/lib/ui/phone/pages/home/home_grades.dart b/firka/lib/ui/phone/pages/home/home_grades.dart
index 35e98ba..c505a9b 100644
--- a/firka/lib/ui/phone/pages/home/home_grades.dart
+++ b/firka/lib/ui/phone/pages/home/home_grades.dart
@@ -146,18 +146,6 @@ class _HomeGradesScreen extends FirkaState<HomeGradesScreen> {
 
         double avg = double.nan;
         if (subjectGrades.isNotEmpty) {
-          for (var grade in subjectGrades) {
-            if (grade.valueType.name == "Szazalekos") {
-              grade.valueType = NameUidDesc(
-                uid: "1,Osztalyzat",
-                name: "Osztalyzat",
-                description: "",
-              );
-              if (grade.numericValue != null) {
-                grade.numericValue = percentageToGrade(grade.numericValue!);
-              }
-            }
-          }
           avg = grades!.response!.getAverageBySubject(subject);
         }
 
diff --git a/firka/lib/ui/phone/widgets/grade_chart.dart b/firka/lib/ui/phone/widgets/grade_chart.dart
index 918874d..78bb8fe 100644
--- a/firka/lib/ui/phone/widgets/grade_chart.dart
+++ b/firka/lib/ui/phone/widgets/grade_chart.dart
@@ -33,6 +33,10 @@ class _GradeChartState extends State<GradeChart> {
     double totalWeight = 0;
     for (final g in grades) {
       if (g.subject.uid != subjectUid) continue;
+      final name = g.valueType.name.toLowerCase();
+      final isPercentage =
+          name.contains('szazalek') || name.contains('percent');
+      if (isPercentage) continue;
       final v = g.numericValue;
       final w = g.weightPercentage;
       if (v != null && w != null) {
diff --git a/firka_common/lib/ui/components/grade_helpers.dart b/firka_common/lib/ui/components/grade_helpers.dart
index 7d28172..d0b98f6 100644
--- a/firka_common/lib/ui/components/grade_helpers.dart
+++ b/firka_common/lib/ui/components/grade_helpers.dart
@@ -86,6 +86,14 @@ extension GradeListExtension on List<Grade> {
 
     for (var grade in this) {
       if (grade.subject.uid == subject.uid) {
+        final name = grade.valueType.name.toLowerCase();
+        final isPercentage =
+            name.contains('szazalek') || name.contains('percent');
+
+        if (isPercentage) {
+          continue;
+        }
+
         if (grade.numericValue != null) {
           var weight = (grade.weightPercentage ?? 100) / 100.0;
           weightTotal += weight;
@@ -95,6 +103,10 @@ extension GradeListExtension on List<Grade> {
       }
     }
 
+    if (weightTotal == 0) {
+      return double.nan;
+    }
+
     return sum / weightTotal;
   }
 }