diff --git a/src/com/android/settings/Utils.java b/src/com/android/settings/Utils.java
index 68b1a48..f9f4cdf 100644
--- a/src/com/android/settings/Utils.java
+++ b/src/com/android/settings/Utils.java
@@ -63,6 +63,7 @@
 import android.os.Binder;
 import android.os.Build;
 import android.os.Bundle;
+import android.os.Environment;
 import android.os.IBinder;
 import android.os.INetworkManagementService;
 import android.os.RemoteException;
@@ -97,7 +98,6 @@
 import androidx.annotation.ColorInt;
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
-import androidx.annotation.StringRes;
 import androidx.annotation.VisibleForTesting;
 import androidx.core.graphics.drawable.IconCompat;
 import androidx.core.graphics.drawable.RoundedBitmapDrawable;
@@ -1295,4 +1295,15 @@
                 com.android.internal.R.bool.config_dreamsOnlyEnabledForDockUser);
         return dreamsSupported && (!dreamsOnlyEnabledForDockUser || canCurrentUserDream(context));
     }
+
+    /**
+     * Get private total size directly.
+     * Referred from StorageManager
+     */
+    public static long getPrimaryStorageSize() {
+        // TODO(b/288103116): remove this method once support by StorageManager.
+        return Environment.getDataDirectory().getTotalSpace()
+                + Environment.getRootDirectory().getTotalSpace();
+    }
+
 }
diff --git a/src/com/android/settings/deviceinfo/StorageCategoryFragment.java b/src/com/android/settings/deviceinfo/StorageCategoryFragment.java
index 52f453d..d1d4cbe 100644
--- a/src/com/android/settings/deviceinfo/StorageCategoryFragment.java
+++ b/src/com/android/settings/deviceinfo/StorageCategoryFragment.java
@@ -211,7 +211,9 @@
 
         setLoading(false /* loading */, false /* animate */);
 
-        final long privateUsedBytes = mStorageInfo.totalBytes - mStorageInfo.freeBytes;
+        // TODO(b/288103116): replace with  new API to get TotalBytes before rounding
+        //  once support by StorageManager.
+        final long privateUsedBytes = Utils.getPrimaryStorageSize() - mStorageInfo.freeBytes;
         mPreferenceController.setVolume(mSelectedStorageEntry.getVolumeInfo());
         mPreferenceController.setUsedSize(privateUsedBytes);
         mPreferenceController.setTotalSize(mStorageInfo.totalBytes);
diff --git a/src/com/android/settings/deviceinfo/StorageDashboardFragment.java b/src/com/android/settings/deviceinfo/StorageDashboardFragment.java
index f31f2be..4138057 100644
--- a/src/com/android/settings/deviceinfo/StorageDashboardFragment.java
+++ b/src/com/android/settings/deviceinfo/StorageDashboardFragment.java
@@ -387,7 +387,9 @@
 
         setLoading(false /* loading */, false /* animate */);
 
-        final long privateUsedBytes = mStorageInfo.totalBytes - mStorageInfo.freeBytes;
+        // TODO(b/288103116): replace with  new API to get TotalBytes before rounding
+        //  once support by StorageManager.
+        final long privateUsedBytes = Utils.getPrimaryStorageSize() - mStorageInfo.freeBytes;
         mPreferenceController.setVolume(mSelectedStorageEntry.getVolumeInfo());
         mPreferenceController.setUsedSize(privateUsedBytes);
         mPreferenceController.setTotalSize(mStorageInfo.totalBytes);
diff --git a/src/com/android/settings/deviceinfo/TopLevelStoragePreferenceController.java b/src/com/android/settings/deviceinfo/TopLevelStoragePreferenceController.java
index e682783..43dc9dd 100644
--- a/src/com/android/settings/deviceinfo/TopLevelStoragePreferenceController.java
+++ b/src/com/android/settings/deviceinfo/TopLevelStoragePreferenceController.java
@@ -74,10 +74,14 @@
         return ThreadUtils.postOnBackgroundThread(() -> {
             final PrivateStorageInfo info = PrivateStorageInfo.getPrivateStorageInfo(
                     getStorageManagerVolumeProvider());
-            storageCacheHelper.cacheUsedSize(info.totalBytes - info.freeBytes);
+
+            // TODO(b/288103116): replace with  new API to get TotalBytes before rounding
+            //  once support by StorageManager.
+            long usedBytes = Utils.getPrimaryStorageSize() - info.freeBytes;
+            storageCacheHelper.cacheUsedSize(usedBytes);
             ThreadUtils.postOnMainThread(() -> {
                 preference.setSummary(
-                        getSummary(info.totalBytes - info.freeBytes, info.totalBytes));
+                        getSummary(usedBytes, info.totalBytes));
             });
         });
     }
diff --git a/src/com/android/settings/deviceinfo/storage/StorageUsageProgressBarPreferenceController.java b/src/com/android/settings/deviceinfo/storage/StorageUsageProgressBarPreferenceController.java
index be2a64a..23559d4 100644
--- a/src/com/android/settings/deviceinfo/storage/StorageUsageProgressBarPreferenceController.java
+++ b/src/com/android/settings/deviceinfo/storage/StorageUsageProgressBarPreferenceController.java
@@ -26,6 +26,7 @@
 import androidx.preference.PreferenceScreen;
 
 import com.android.settings.R;
+import com.android.settings.Utils;
 import com.android.settings.core.BasePreferenceController;
 import com.android.settingslib.utils.ThreadUtils;
 import com.android.settingslib.widget.UsageProgressBarPreference;
@@ -92,7 +93,9 @@
                 if (mStorageEntry.isPrivate()) {
                     // StorageStatsManager can only query private storages.
                     mTotalBytes = mStorageStatsManager.getTotalBytes(mStorageEntry.getFsUuid());
-                    mUsedBytes = mTotalBytes
+                    // TODO(b/288103116): replace with  new API to get TotalBytes before rounding
+                    //  once support by StorageManager.
+                    mUsedBytes = Utils.getPrimaryStorageSize()
                             - mStorageStatsManager.getFreeBytes(mStorageEntry.getFsUuid());
                 } else {
                     final File rootFile = mStorageEntry.getPath();