diff --git a/HeartbeatSender.cs b/HeartbeatSender.cs
index 8278b25..19b3a93 100644
--- a/HeartbeatSender.cs
+++ b/HeartbeatSender.cs
@@ -168,7 +168,10 @@ namespace HeartbeatSender
         private float GetTotalMemoryInMB()
         {
             var computerInfo = new ComputerInfo();
-            return computerInfo.TotalPhysicalMemory / (1024f * 1024f); // 轉 MB
+            var totalMB = computerInfo.TotalPhysicalMemory / (1024f);
+            var availableMB = computerInfo.AvailablePhysicalMemory / (1024f);
+            var usedMB = totalMB - availableMB;
+            return usedMB; // 轉 MB
         }
         private float GetDiskTotalSizeInGB(string driveLetter = "C")
         {