diff --git a/include/reHDD.h b/include/reHDD.h
index d62b78f..b8b9cfa 100644
--- a/include/reHDD.h
+++ b/include/reHDD.h
@@ -23,14 +23,14 @@
 #define SOFTWARE_VERSION  "alpha"
 #define HARDWARE_VERSION  "generic"
 
-#define LOG_LEVEL_HIGH  //log everything, like drive scann thread
+//#define LOG_LEVEL_HIGH  //log everything, like drive scann thread
 #ifndef LOG_LEVEL_HIGH
 #define LOG_LEVEL_LOW   //log only user actions and tasks 
 #endif
 
 // Logic
 //#define DRYRUN //don´t touch the drives
-#define DEMO_DRIVE_SIZE 1024*1024*256 // 256MB used for shredding only
+//#define DEMO_DRIVE_SIZE 1024*1024*256 // 256MB used for shredding only
 #define FROZEN_ALERT //show alert if drive is frozen
 #define ZERO_CHECK_ALERT //check drive after shred if all bytes are zero, show alert if this fails
 
diff --git a/include/shred.h b/include/shred.h
index 18b5d12..6306762 100644
--- a/include/shred.h
+++ b/include/shred.h
@@ -40,13 +40,14 @@ private:
     fileDescriptor driveFileDiscr;
     unsigned char caChunk[CHUNK_SIZE];
     unsigned long ulDriveByteSize;
+    unsigned long ulDriveByteOverallCount = 0; //all bytes shredded in all iterations + checking -> used for progress calculation
     double d32Percent = 0.0;
     double d32TmpPercent = 0.0;
 
-    inline double calcProgress(unsigned long ulDriveByteIndex, unsigned int uiIteration);
+    inline double calcProgress();
     int iRewindDrive(fileDescriptor file);
     unsigned long getDriveSizeInBytes(fileDescriptor file);
-    unsigned int uiCalcChecksum(fileDescriptor file);
+    unsigned int uiCalcChecksum(fileDescriptor file, Drive* drive, int* ipSignalFd);
     void cleanup();
 
 };
diff --git a/src/shred.cpp b/src/shred.cpp
index 84180ad..6031184 100644
--- a/src/shred.cpp
+++ b/src/shred.cpp
@@ -120,14 +120,13 @@ int Shred::shredDrive(Drive* drive, int* ipSignalFd)
                             return -1;
                         }
                     ulDriveByteCounter += iByteShredded;
-
-                    d32Percent = this->calcProgress(ulDriveByteCounter, (uiShredIterationCounter+1));
+                    ulDriveByteOverallCount += iByteShredded;
+                    d32Percent = this->calcProgress();
 
 #ifdef LOG_LEVEL_HIGH
-                    Logger::logThis()->info("Shred-Task: ByteCount: " + to_string(ulDriveByteCounter) + " - progress: " + to_string(d32Percent) + " - Drive: " + drive->getSerial());
+                    Logger::logThis()->info("Shred-Task: ByteCount: " + to_string(ulDriveByteCounter) +  " - iteration: " + to_string((uiShredIterationCounter+1)) + " - progress: " + to_string(d32Percent) + " - Drive: " + drive->getSerial());
 #endif
-
-                    if((d32Percent-d32TmpPercent) >= 0.09)
+                    if((d32Percent-d32TmpPercent) >= 0.01)
                         {
                             drive->setTaskPercentage(d32TmpPercent);
                             d32TmpPercent = d32Percent;
@@ -155,7 +154,7 @@ int Shred::shredDrive(Drive* drive, int* ipSignalFd)
         } //end all shred iterations
 
 #ifdef ZERO_CHECK_ALERT
-    drive->u32DriveChecksumAferShredding = uiCalcChecksum(driveFileDiscr);
+    drive->u32DriveChecksumAferShredding = uiCalcChecksum(driveFileDiscr, drive, ipSignalFd);
 #ifdef LOG_LEVEL_HIGH
     if (drive->u32DriveChecksumAferShredding != 0)
         {
@@ -176,7 +175,6 @@ int Shred::shredDrive(Drive* drive, int* ipSignalFd)
             drive->setTaskPercentage(0.0);
             Logger::logThis()->info("Finished shred for: " + drive->getModelName() + "-" +  drive->getSerial());
         }
-
     return 0;
 }
 /**
@@ -185,15 +183,14 @@ int Shred::shredDrive(Drive* drive, int* ipSignalFd)
  * \param	current shred iteration
  * \return  double percentage
  */
-double Shred::calcProgress(unsigned long ulDriveByteIndex, unsigned int uiIteration)
+double Shred::calcProgress()
 {
     unsigned int uiMaxShredIteration = SHRED_ITERATIONS;
 
 #ifdef ZERO_CHECK_ALERT
     uiMaxShredIteration++; //increment because we will check after SHRED_ITERATIONS the drive for non-zero bytes
 #endif
-
-    return (double) (100.0f/((double)this->ulDriveByteSize)*((double) ulDriveByteIndex) / ((double) uiIteration / (double) uiMaxShredIteration) );
+    return (double) (((double) ulDriveByteOverallCount) / ((double)this->ulDriveByteSize*uiMaxShredIteration))*100.0f;
 }
 
 int Shred::iRewindDrive(fileDescriptor file)
@@ -224,7 +221,7 @@ unsigned long Shred::getDriveSizeInBytes(fileDescriptor file)
     return ulDriveSizeTmp;
 }
 
-unsigned int Shred::uiCalcChecksum(fileDescriptor file)
+unsigned int Shred::uiCalcChecksum(fileDescriptor file,Drive* drive, int* ipSignalFd)
 {
     unsigned int uiChecksum = 0;
     unsigned long ulDriveByteCounter = 0U;
@@ -247,6 +244,21 @@ unsigned int Shred::uiCalcChecksum(fileDescriptor file)
                     uiChecksum += caChunk[iReadBytesCounter];
                 }
             ulDriveByteCounter += iReadBytes;
+            ulDriveByteOverallCount += ulDriveByteCounter;
+
+            d32Percent = this->calcProgress();
+
+#ifdef LOG_LEVEL_HIGH
+            Logger::logThis()->info("Shred-Task (Checksum): ByteCount: " + to_string(ulDriveByteCounter) + " - progress: " + to_string(d32Percent) + " - Drive: " + drive->getSerial());
+#endif
+
+            if((d32Percent-d32TmpPercent) >= 0.09)
+                {
+                    drive->setTaskPercentage(d32TmpPercent);
+                    d32TmpPercent = d32Percent;
+                    write(*ipSignalFd, "A",1);
+                }
+
         }
     return uiChecksum;
 }
diff --git a/src/tui.cpp b/src/tui.cpp
index ce85d94..6d2b4c0 100644
--- a/src/tui.cpp
+++ b/src/tui.cpp
@@ -128,7 +128,7 @@ void TUI::updateTUI(list <Drive>* plistDrives, uint8_t u8SelectedEntry)
                         }
 
 #ifdef ZERO_CHECK_ALERT
-                    if(bSelectedEntry && it->bWasShredded && (it->u32DriveChecksumAferShredding != 42U))
+                    if(bSelectedEntry && it->bWasShredded && (it->u32DriveChecksumAferShredding != 0U))
                         {
                             dialog=createZeroChecksumWarning(70, 16, ((u16StdscrX)-(int)(u16StdscrX/2)-20),(int)(u16StdscrY/2)-8, it->getPath(), it->getModelFamily(), it->getModelName(), it->getSerial(), it->u32DriveChecksumAferShredding);
                             wrefresh(dialog);