Index: src/wp-admin/includes/ms.php
===================================================================
--- src/wp-admin/includes/ms.php	(revision 35286)
+++ src/wp-admin/includes/ms.php	(working copy)
@@ -29,8 +29,8 @@
 
 	$file_size = filesize( $file['tmp_name'] );
 	if ( $space_left < $file_size )
-		$file['error'] = sprintf( __( 'Not enough space to upload. %1$s KB needed.' ), number_format( ($file_size - $space_left) /1024 ) );
-	if ( $file_size > ( 1024 * get_site_option( 'fileupload_maxk', 1500 ) ) )
+		$file['error'] = sprintf( __( 'Not enough space to upload. %1$s KB needed.' ), number_format( ($file_size - $space_left) / KB_IN_BYTES ) );
+	if ( $file_size > ( KB_IN_BYTES * get_site_option( 'fileupload_maxk', 1500 ) ) )
 		$file['error'] = sprintf(__('This file is too big. Files must be less than %1$s KB in size.'), get_site_option( 'fileupload_maxk', 1500 ) );
 	if ( upload_is_user_over_quota( false ) ) {
 		$file['error'] = __( 'You have used your space quota. Please delete files before uploading.' );
@@ -1104,4 +1104,4 @@
 });
 </script>
 <?php
-}
\ No newline at end of file
+}
Index: src/wp-includes/cache.php
===================================================================
--- src/wp-includes/cache.php	(revision 35286)
+++ src/wp-includes/cache.php	(working copy)
@@ -691,7 +691,7 @@
 		echo "</p>";
 		echo '<ul>';
 		foreach ($this->cache as $group => $cache) {
-			echo "<li><strong>Group:</strong> $group - ( " . number_format( strlen( serialize( $cache ) ) / 1024, 2 ) . 'k )</li>';
+			echo "<li><strong>Group:</strong> $group - ( " . number_format( strlen( serialize( $cache ) ) / KB_IN_BYTES, 2 ) . 'k )</li>';
 		}
 		echo '</ul>';
 	}
Index: src/wp-includes/functions.php
===================================================================
--- src/wp-includes/functions.php	(revision 35286)
+++ src/wp-includes/functions.php	(working copy)
@@ -210,12 +210,11 @@
  */
 function size_format( $bytes, $decimals = 0 ) {
 	$quant = array(
-		// ========================= Origin ====
-		'TB' => 1099511627776,  // pow( 1024, 4)
-		'GB' => 1073741824,     // pow( 1024, 3)
-		'MB' => 1048576,        // pow( 1024, 2)
-		'kB' => 1024,           // pow( 1024, 1)
-		'B'  => 1,              // pow( 1024, 0)
+		'TB' => TB_IN_BYTES,
+		'GB' => GB_IN_BYTES,
+		'MB' => MB_IN_BYTES,
+		'kB' => KB_IN_BYTES,
+		'B'  => 1,
 	);
 
 	foreach ( $quant as $unit => $mag ) {
Index: src/wp-includes/media.php
===================================================================
--- src/wp-includes/media.php	(revision 35286)
+++ src/wp-includes/media.php	(working copy)
@@ -2611,11 +2611,11 @@
 	$size  = strtolower( $size );
 	$bytes = (int) $size;
 	if ( strpos( $size, 'k' ) !== false )
-		$bytes = intval( $size ) * 1024;
+		$bytes = intval( $size ) * KB_IN_BYTES;
 	elseif ( strpos( $size, 'm' ) !== false )
-		$bytes = intval($size) * 1024 * 1024;
+		$bytes = intval($size) * MB_IN_BYTES;
 	elseif ( strpos( $size, 'g' ) !== false )
-		$bytes = intval( $size ) * 1024 * 1024 * 1024;
+		$bytes = intval( $size ) * GB_IN_BYTES;
 	return $bytes;
 }
 
Index: src/wp-includes/ms-functions.php
===================================================================
--- src/wp-includes/ms-functions.php	(revision 35286)
+++ src/wp-includes/ms-functions.php	(working copy)
@@ -1874,7 +1874,7 @@
 	if ( ! is_array( $upload ) || defined( 'WP_IMPORTING' ) || get_site_option( 'upload_space_check_disabled' ) )
 		return $upload;
 
-	if ( strlen( $upload['bits'] )  > ( 1024 * get_site_option( 'fileupload_maxk', 1500 ) ) )
+	if ( strlen( $upload['bits'] )  > ( KB_IN_BYTES * get_site_option( 'fileupload_maxk', 1500 ) ) )
 		return sprintf( __( 'This file is too big. Files must be less than %d KB in size.' ) . '<br />', get_site_option( 'fileupload_maxk', 1500 ));
 
 	return $upload;
@@ -2278,7 +2278,7 @@
 	$space_used = apply_filters( 'pre_get_space_used', false );
 	if ( false === $space_used ) {
 		$upload_dir = wp_upload_dir();
-		$space_used = get_dirsize( $upload_dir['basedir'] ) / 1024 / 1024;
+		$space_used = get_dirsize( $upload_dir['basedir'] ) / MB_IN_BYTES;
 	}
 
 	return $space_used;
@@ -2322,11 +2322,11 @@
 	if ( $allowed < 0 ) {
 		$allowed = 0;
 	}
-	$space_allowed = $allowed * 1024 * 1024;
+	$space_allowed = $allowed * MB_IN_BYTES;
 	if ( get_site_option( 'upload_space_check_disabled' ) )
 		return $space_allowed;
 
-	$space_used = get_space_used() * 1024 * 1024;
+	$space_used = get_space_used() * MB_IN_BYTES;
 
 	if ( ( $space_allowed - $space_used ) <= 0 )
 		return 0;
@@ -2353,7 +2353,7 @@
  * @return int of upload size limit in bytes
  */
 function upload_size_limit_filter( $size ) {
-	$fileupload_maxk = 1024 * get_site_option( 'fileupload_maxk', 1500 );
+	$fileupload_maxk = KB_IN_BYTES * get_site_option( 'fileupload_maxk', 1500 );
 	if ( get_site_option( 'upload_space_check_disabled' ) )
 		return min( $size, $fileupload_maxk );