diff --git a/changelog.d/3846.feature b/changelog.d/3846.feature
new file mode 100644
index 0000000000..453c11d3f8
--- /dev/null
+++ b/changelog.d/3846.feature
@@ -0,0 +1 @@
+Add synapse_admin_mau:registered_reserved_users metric to expose number of real reaserved users 
diff --git a/synapse/app/homeserver.py b/synapse/app/homeserver.py
index 3eb5b663de..ac97e19649 100755
--- a/synapse/app/homeserver.py
+++ b/synapse/app/homeserver.py
@@ -307,6 +307,10 @@ class SynapseHomeServer(HomeServer):
 # Gauges to expose monthly active user control metrics
 current_mau_gauge = Gauge("synapse_admin_mau:current", "Current MAU")
 max_mau_gauge = Gauge("synapse_admin_mau:max", "MAU Limit")
+registered_reserved_users_mau_gauge = Gauge(
+    "synapse_admin_mau:registered_reserved_users",
+    "Registered users with reserved threepids"
+)
 
 
 def setup(config_options):
@@ -531,10 +535,14 @@ def run(hs):
 
     @defer.inlineCallbacks
     def generate_monthly_active_users():
-        count = 0
+        current_mau_count = 0
+        reserved_count = 0
+        store = hs.get_datastore()
         if hs.config.limit_usage_by_mau:
-            count = yield hs.get_datastore().get_monthly_active_count()
-        current_mau_gauge.set(float(count))
+            current_mau_count = yield store.get_monthly_active_count()
+            reserved_count = yield store.get_registered_reserved_users_count()
+        current_mau_gauge.set(float(current_mau_count))
+        registered_reserved_users_mau_gauge.set(float(reserved_count))
         max_mau_gauge.set(float(hs.config.max_mau_value))
 
     hs.get_datastore().initialise_reserved_users(
diff --git a/synapse/storage/monthly_active_users.py b/synapse/storage/monthly_active_users.py
index b890c152db..59580949f1 100644
--- a/synapse/storage/monthly_active_users.py
+++ b/synapse/storage/monthly_active_users.py
@@ -146,6 +146,23 @@ class MonthlyActiveUsersStore(SQLBaseStore):
             return count
         return self.runInteraction("count_users", _count_users)
 
+    @defer.inlineCallbacks
+    def get_registered_reserved_users_count(self):
+        """Of the reserved threepids defined in config, how many are associated
+        with registered users?
+
+        Returns:
+            Defered[int]: Number of real reserved users
+        """
+        count = 0
+        for tp in self.hs.config.mau_limits_reserved_threepids:
+            user_id = yield self.hs.get_datastore().get_user_id_by_threepid(
+                tp["medium"], tp["address"]
+            )
+            if user_id:
+                count = count + 1
+        defer.returnValue(count)
+
     @defer.inlineCallbacks
     def upsert_monthly_active_user(self, user_id):
         """
diff --git a/tests/storage/test_monthly_active_users.py b/tests/storage/test_monthly_active_users.py
index ccfc21b7fc..686f12a0dc 100644
--- a/tests/storage/test_monthly_active_users.py
+++ b/tests/storage/test_monthly_active_users.py
@@ -183,3 +183,34 @@ class MonthlyActiveUsersTestCase(HomeserverTestCase):
         self.store.populate_monthly_active_users('user_id')
         self.pump()
         self.store.upsert_monthly_active_user.assert_not_called()
+
+    def test_get_reserved_real_user_account(self):
+        # Test no reserved users, or reserved threepids
+        count = self.store.get_registered_reserved_users_count()
+        self.assertEquals(self.get_success(count), 0)
+        # Test reserved users but no registered users
+
+        user1 = '@user1:example.com'
+        user2 = '@user2:example.com'
+        user1_email = 'user1@example.com'
+        user2_email = 'user2@example.com'
+        threepids = [
+            {'medium': 'email', 'address': user1_email},
+            {'medium': 'email', 'address': user2_email},
+        ]
+        self.hs.config.mau_limits_reserved_threepids = threepids
+        self.store.initialise_reserved_users(threepids)
+        self.pump()
+        count = self.store.get_registered_reserved_users_count()
+        self.assertEquals(self.get_success(count), 0)
+
+        # Test reserved registed users
+        self.store.register(user_id=user1, token="123", password_hash=None)
+        self.store.register(user_id=user2, token="456", password_hash=None)
+        self.pump()
+
+        now = int(self.hs.get_clock().time_msec())
+        self.store.user_add_threepid(user1, "email", user1_email, now, now)
+        self.store.user_add_threepid(user2, "email", user2_email, now, now)
+        count = self.store.get_registered_reserved_users_count()
+        self.assertEquals(self.get_success(count), len(threepids))