diff --git a/IRaCIS.Core.Application/Service/Reading/Dto/ReadingCalculateViewModel.cs b/IRaCIS.Core.Application/Service/Reading/Dto/ReadingCalculateViewModel.cs
index d35992f04..e71ab5fc5 100644
--- a/IRaCIS.Core.Application/Service/Reading/Dto/ReadingCalculateViewModel.cs
+++ b/IRaCIS.Core.Application/Service/Reading/Dto/ReadingCalculateViewModel.cs
@@ -301,10 +301,15 @@ namespace IRaCIS.Core.Application.Service.Reading.Dto
         public decimal? LipidAngle { get; set; }
 
 
-        public decimal? Avg { get {
-
-                return (  FirstData + SecondData  + ThirdData) / 3;
-            } }
+        public decimal? Avg
+        {
+            get
+            {
+                var values = new[] { FirstData, SecondData, ThirdData };
+                var avg = values.Where(x => x.HasValue).Select(x => x.Value).DefaultIfEmpty(0).Average();
+                return avg;
+            }
+        }
     }