diff --git a/src/Miscellaneous/IDPostCount.coffee b/src/Miscellaneous/IDPostCount.coffee
new file mode 100644
index 000000000..8248e7b79
--- /dev/null
+++ b/src/Miscellaneous/IDPostCount.coffee
@@ -0,0 +1,22 @@
+IDPostCount =
+  init: ->
+    return unless g.VIEW is 'thread' and Conf['Count Posts by ID']
+    Callbacks.Thread.push
+      name: 'Count Posts by ID'
+      cb:   -> IDPostCount.thread = @
+    Callbacks.Post.push
+      name: 'Count Posts by ID'
+      cb:   @node
+
+  node: ->
+    if @nodes.uniqueID and @thread is IDPostCount.thread
+      $.on $('span.hand', @nodes.uniqueID), 'mouseover', IDPostCount.count
+
+  count: ->
+    {uniqueID} = Get.postFromNode(@).info
+    n = 0
+    IDPostCount.thread.posts.forEach (post) ->
+      n++ if post.info.uniqueID is uniqueID
+    @title = "#{n} post#{if n is 1 then '' else 's'} by this ID"
+
+return IDPostCount
diff --git a/src/config/Config.coffee b/src/config/Config.coffee
index bead6a5ce..f79031b32 100644
--- a/src/config/Config.coffee
+++ b/src/config/Config.coffee
@@ -97,6 +97,10 @@ Config =
         true
         'Assign unique colors to user IDs on boards that use them'
       ]
+      'Count Posts by ID': [
+        true
+        'Display number of posts in the thread when hovering over an ID.'
+      ]
       'Remove Spoilers': [
         false
         'Remove all spoilers in text.'
diff --git a/src/main/Main.coffee b/src/main/Main.coffee
index 5d59cd588..d561c0fa8 100644
--- a/src/main/Main.coffee
+++ b/src/main/Main.coffee
@@ -438,6 +438,7 @@ Main =
     ['Fourchan thingies',         Fourchan]
     ['Color User IDs',            IDColor]
     ['Highlight by User ID',      IDHighlight]
+    ['Count Posts by ID',         IDPostCount]
     ['Custom CSS',                CustomCSS]
     ['Thread Links',              ThreadLinks]
     ['Linkify',                   Linkify]