diff --git a/heat/common/timeutils.py b/heat/common/timeutils.py
index e31e9be04b..eca6291b05 100644
--- a/heat/common/timeutils.py
+++ b/heat/common/timeutils.py
@@ -15,6 +15,7 @@
 Utilities for handling ISO 8601 duration format.
 """
 
+import datetime
 import random
 import re
 import time
@@ -80,3 +81,12 @@ def retry_backoff_delay(attempt, scale_factor=1.0, jitter_max=0.0):
     if jitter_max == 0.0:
         return exp
     return exp + random.random() * jitter_max
+
+
+def round_to_seconds(dt):
+    """Round a datetime to the nearest second."""
+    rounding = 0
+    if dt.microsecond >= 500000:
+        rounding = 1
+    return dt + datetime.timedelta(0, rounding,
+                                   -dt.microsecond)
diff --git a/heat/engine/stack.py b/heat/engine/stack.py
index e9d3c36601..a2c35acc32 100644
--- a/heat/engine/stack.py
+++ b/heat/engine/stack.py
@@ -33,6 +33,7 @@ from heat.common.i18n import _LI
 from heat.common.i18n import _LW
 from heat.common import identifier
 from heat.common import lifecycle_plugin_utils
+from heat.common import timeutils
 from heat.engine import dependencies
 from heat.engine import environment
 from heat.engine import event
@@ -1688,8 +1689,10 @@ class Stack(collections.Mapping):
         '''
         Time elapsed in seconds since the stack operation started.
         '''
-        start_time = self.updated_time or self.created_time
-        return (datetime.datetime.utcnow() - start_time).seconds
+        start_time = timeutils.round_to_seconds(self.updated_time or
+                                                self.created_time)
+        nowish = timeutils.round_to_seconds(datetime.datetime.utcnow())
+        return (nowish - start_time).seconds
 
     def time_remaining(self):
         '''
diff --git a/heat/tests/test_stack.py b/heat/tests/test_stack.py
index eee61e20dd..b8aceaf31d 100644
--- a/heat/tests/test_stack.py
+++ b/heat/tests/test_stack.py
@@ -111,6 +111,17 @@ class StackTest(common.HeatTestCase):
                                                                  10, 10, 0)
         self.assertEqual(600, self.stack.time_elapsed())
 
+    @mock.patch.object(stack, 'datetime')
+    def test_time_elapsed_ms(self, mock_dt):
+        self.stack = stack.Stack(self.ctx, 'test_stack', self.tmpl)
+        # dummy create time 10:00:00
+        self.stack.created_time = datetime.datetime(2015, 7, 27, 10, 5, 0)
+        # mock utcnow set to microsecond offset
+        mock_dt.datetime.utcnow.return_value = datetime.datetime(2015, 7, 27,
+                                                                 10, 4, 59,
+                                                                 750000)
+        self.assertEqual(0, self.stack.time_elapsed())
+
     @mock.patch.object(stack, 'datetime')
     def test_time_elapsed_with_updated_time(self, mock_dt):
         self.stack = stack.Stack(self.ctx, 'test_stack', self.tmpl)
diff --git a/heat/tests/test_timeutils.py b/heat/tests/test_timeutils.py
index 567a502e8d..28ac125c24 100644
--- a/heat/tests/test_timeutils.py
+++ b/heat/tests/test_timeutils.py
@@ -11,6 +11,7 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+import datetime
 from testtools import matchers
 
 from heat.common import timeutils as util
@@ -157,3 +158,17 @@ class RetryBackoffJitterTest(common.HeatTestCase):
                 self.attempt, self.scale_factor, self.jitter_max)
             self.assertThat(delay, matchers.GreaterThan(self.delay_from))
             self.assertThat(delay, matchers.LessThan(self.delay_to))
+
+
+class RoundToSecondsTest(common.HeatTestCase):
+
+    scenarios = [('down', dict(in_secs=5, in_ms=12345, out_secs=5)),
+                 ('up', dict(in_secs=5, in_ms=501000, out_secs=6)),
+                 ('same', dict(in_secs=5, in_ms=0, out_secs=5))]
+
+    def test_rounding(self):
+        inp = datetime.datetime(2015, 7, 27, 4,
+                                34, self.in_secs, self.in_ms)
+        exp = datetime.datetime(2015, 7, 27, 4,
+                                34, self.out_secs, 0)
+        self.assertEqual(exp, util.round_to_seconds(inp))