Index: includes/Article.php
===================================================================
--- includes/Article.php	(revision 42410)
+++ includes/Article.php	(working copy)
@@ -2146,6 +2146,7 @@
 
 		# Hack for big sites
 		$bigHistory = $this->isBigDeletion();
+		$revisions = $this->estimateRevisionCount();
 		if( $bigHistory && !$this->mTitle->userCan( 'bigdelete' ) ) {
 			global $wgLang, $wgDeleteRevisionsLimit;
 			$wgOut->wrapWikiMsg( "<div class='error'>\n$1</div>\n",
@@ -2177,6 +2178,9 @@
 					array( 'delete-warning-toobig', $wgLang->formatNum( $wgDeleteRevisionsLimit ) ) );
 			}
 		}
+		if( $revisions > 3 && !$confirm ) {
+			$wgOut->wrapWikiMsg(''.wfMsg('revdelete-count', $revisions).'');
+		}
 
 		return $this->confirmDelete( $reason );
 	}
Index: languages/messages/MessagesEn.php
===================================================================
--- languages/messages/MessagesEn.php	(revision 42410)
+++ languages/messages/MessagesEn.php	(working copy)
@@ -1314,6 +1314,7 @@
 'revdelete-unhid'             => 'unhid $1',
 'revdelete-log-message'       => '$1 for $2 {{PLURAL:$2|revision|revisions}}',
 'logdelete-log-message'       => '$1 for $2 {{PLURAL:$2|event|events}}',
+'revdelete-count'	      => 'The article currently has $1 edits worth of history, deleting the article will also remove that history.',
 
 # Suppression log
 'suppressionlog'     => 'Suppression log',