diff --git a/common_video/BUILD.gn b/common_video/BUILD.gn
index ccb93ee..c0cd959 100644
--- a/common_video/BUILD.gn
+++ b/common_video/BUILD.gn
@@ -13,6 +13,8 @@
 
   sources = [
     "bitrate_adjuster.cc",
+    "frame_rate_estimator.cc",
+    "frame_rate_estimator.h",
     "h264/h264_bitstream_parser.cc",
     "h264/h264_bitstream_parser.h",
     "h264/h264_common.cc",
@@ -42,6 +44,8 @@
   deps = [
     "../api:scoped_refptr",
     "../api/task_queue",
+    "../api/units:time_delta",
+    "../api/units:timestamp",
     "../api/video:encoded_image",
     "../api/video:video_bitrate_allocation",
     "../api/video:video_bitrate_allocator",
@@ -78,6 +82,7 @@
 
     sources = [
       "bitrate_adjuster_unittest.cc",
+      "frame_rate_estimator_unittest.cc",
       "h264/h264_bitstream_parser_unittest.cc",
       "h264/pps_parser_unittest.cc",
       "h264/profile_level_id_unittest.cc",
@@ -102,6 +107,7 @@
       "../rtc_base:checks",
       "../rtc_base:rtc_base_approved",
       "../rtc_base:rtc_base_tests_utils",
+      "../system_wrappers:system_wrappers",
       "../test:fileutils",
       "../test:test_main",
       "../test:test_support",
diff --git a/common_video/frame_rate_estimator.cc b/common_video/frame_rate_estimator.cc
new file mode 100644
index 0000000..86f0722
--- /dev/null
+++ b/common_video/frame_rate_estimator.cc
@@ -0,0 +1,55 @@
+/*
+ *  Copyright (c) 2019 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "common_video/frame_rate_estimator.h"
+
+#include "rtc_base/time_utils.h"
+
+namespace webrtc {
+
+FrameRateEstimator::FrameRateEstimator(TimeDelta averaging_window)
+    : averaging_window_(averaging_window) {}
+
+void FrameRateEstimator::OnFrame(Timestamp time) {
+  CullOld(time);
+  frame_times_.push_back(time);
+}
+
+absl::optional<double> FrameRateEstimator::GetAverageFps() const {
+  if (frame_times_.size() < 2) {
+    return absl::nullopt;
+  }
+  TimeDelta time_span = frame_times_.back() - frame_times_.front();
+  if (time_span < TimeDelta::us(1)) {
+    return absl::nullopt;
+  }
+  TimeDelta avg_frame_interval = time_span / (frame_times_.size() - 1);
+
+  return static_cast<double>(rtc::kNumMicrosecsPerSec) /
+         avg_frame_interval.us();
+}
+
+absl::optional<double> FrameRateEstimator::GetAverageFps(Timestamp now) {
+  CullOld(now);
+  return GetAverageFps();
+}
+
+void FrameRateEstimator::Reset() {
+  frame_times_.clear();
+}
+
+void FrameRateEstimator::CullOld(Timestamp now) {
+  while (!frame_times_.empty() &&
+         frame_times_.front() + averaging_window_ < now) {
+    frame_times_.pop_front();
+  }
+}
+
+}  // namespace webrtc
diff --git a/common_video/frame_rate_estimator.h b/common_video/frame_rate_estimator.h
new file mode 100644
index 0000000..4cdd284
--- /dev/null
+++ b/common_video/frame_rate_estimator.h
@@ -0,0 +1,60 @@
+/*
+ *  Copyright (c) 2019 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef COMMON_VIDEO_FRAME_RATE_ESTIMATOR_H_
+#define COMMON_VIDEO_FRAME_RATE_ESTIMATOR_H_
+
+#include <deque>
+
+#include "absl/types/optional.h"
+#include "api/units/time_delta.h"
+#include "api/units/timestamp.h"
+
+namespace webrtc {
+
+// Class used to estimate a frame-rate using inter-frame intervals.
+// Some notes on usage:
+// This class is intended to accurately estimate the frame rate during a
+// continuous stream. Unlike a traditional rate estimator that looks at number
+// of data points within a time window, if the input stops this implementation
+// will not smoothly fall down towards 0. This is done so that the estimated
+// fps is not affected by edge conditions like if we sample just before or just
+// after the next frame.
+// To avoid problems if a stream is stopped and restarted (where estimated fps
+// could look too low), users of this class should explicitly call Reset() on
+// restart.
+// Also note that this class is not thread safe, it's up to the user to guard
+// against concurrent access.
+class FrameRateEstimator {
+ public:
+  explicit FrameRateEstimator(TimeDelta averaging_window);
+
+  // Insert a frame, potentially culling old frames that falls outside the
+  // averaging window.
+  void OnFrame(Timestamp time);
+
+  // Get the current average FPS, based on the frames currently in the window.
+  absl::optional<double> GetAverageFps() const;
+
+  // Move the window so it ends at |now|, and return the new fps estimate.
+  absl::optional<double> GetAverageFps(Timestamp now);
+
+  // Completely clear the averaging window.
+  void Reset();
+
+ private:
+  void CullOld(Timestamp now);
+  const TimeDelta averaging_window_;
+  std::deque<Timestamp> frame_times_;
+};
+
+}  // namespace webrtc
+
+#endif  // COMMON_VIDEO_FRAME_RATE_ESTIMATOR_H_
diff --git a/common_video/frame_rate_estimator_unittest.cc b/common_video/frame_rate_estimator_unittest.cc
new file mode 100644
index 0000000..9058bac
--- /dev/null
+++ b/common_video/frame_rate_estimator_unittest.cc
@@ -0,0 +1,103 @@
+/*
+ *  Copyright (c) 2019 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "common_video/frame_rate_estimator.h"
+
+#include "system_wrappers/include/clock.h"
+#include "test/gmock.h"
+#include "test/gtest.h"
+
+namespace webrtc {
+namespace {
+constexpr TimeDelta kDefaultWindow = TimeDelta::Millis<1000>();
+}
+
+class FrameRateEstimatorTest : public ::testing::Test {
+ public:
+  FrameRateEstimatorTest() : clock_(123), estimator_(kDefaultWindow) {}
+
+ protected:
+  SimulatedClock clock_;
+  FrameRateEstimator estimator_;
+};
+
+TEST_F(FrameRateEstimatorTest, NoEstimateWithLessThanTwoFrames) {
+  EXPECT_FALSE(estimator_.GetAverageFps());
+  estimator_.OnFrame(clock_.CurrentTime());
+  EXPECT_FALSE(estimator_.GetAverageFps());
+  clock_.AdvanceTime(TimeDelta::ms(33));
+  EXPECT_FALSE(estimator_.GetAverageFps());
+}
+
+TEST_F(FrameRateEstimatorTest, NoEstimateWithZeroSpan) {
+  // Two frames, but they are spanning 0ms so can't estimate frame rate.
+  estimator_.OnFrame(clock_.CurrentTime());
+  estimator_.OnFrame(clock_.CurrentTime());
+  EXPECT_FALSE(estimator_.GetAverageFps());
+}
+
+TEST_F(FrameRateEstimatorTest, SingleSpanFps) {
+  const double kExpectedFps = 30.0;
+  estimator_.OnFrame(clock_.CurrentTime());
+  clock_.AdvanceTime(TimeDelta::seconds(1) / kExpectedFps);
+  estimator_.OnFrame(clock_.CurrentTime());
+  EXPECT_NEAR(*estimator_.GetAverageFps(), kExpectedFps, 0.001);
+}
+
+TEST_F(FrameRateEstimatorTest, AverageFps) {
+  // Insert frames a intervals corresponding to 10fps for half the window, then
+  // 40fps half the window. The average should be 20fps.
+  const double kLowFps = 10.0;
+  const double kHighFps = 30.0;
+  const double kExpectedFps = 20.0;
+
+  const Timestamp start_time = clock_.CurrentTime();
+  while (clock_.CurrentTime() - start_time < kDefaultWindow / 2) {
+    estimator_.OnFrame(clock_.CurrentTime());
+    clock_.AdvanceTime(TimeDelta::seconds(1) / kLowFps);
+  }
+  while (clock_.CurrentTime() - start_time < kDefaultWindow) {
+    estimator_.OnFrame(clock_.CurrentTime());
+    clock_.AdvanceTime(TimeDelta::seconds(1) / kHighFps);
+  }
+
+  EXPECT_NEAR(*estimator_.GetAverageFps(), kExpectedFps, 0.001);
+}
+
+TEST_F(FrameRateEstimatorTest, CullsOldFramesFromAveragingWindow) {
+  // Two frames, just on the border of the 1s window => 1 fps.
+  estimator_.OnFrame(clock_.CurrentTime());
+  clock_.AdvanceTime(kDefaultWindow);
+  estimator_.OnFrame(clock_.CurrentTime());
+  EXPECT_TRUE(estimator_.GetAverageFps());
+  EXPECT_NEAR(*estimator_.GetAverageFps(), 1.0, 0.001);
+
+  // Oldest frame should just be pushed out the window, leaving a single frame
+  // => no estimate possible.
+  clock_.AdvanceTime(TimeDelta::us(1));
+  EXPECT_FALSE(estimator_.GetAverageFps(clock_.CurrentTime()));
+}
+
+TEST_F(FrameRateEstimatorTest, Reset) {
+  estimator_.OnFrame(clock_.CurrentTime());
+  clock_.AdvanceTime(TimeDelta::seconds(1) / 30);
+  estimator_.OnFrame(clock_.CurrentTime());
+  EXPECT_TRUE(estimator_.GetAverageFps());
+
+  // Clear estimator, no estimate should be possible even after inserting one
+  // new frame.
+  estimator_.Reset();
+  EXPECT_FALSE(estimator_.GetAverageFps());
+  clock_.AdvanceTime(TimeDelta::seconds(1) / 30);
+  estimator_.OnFrame(clock_.CurrentTime());
+  EXPECT_FALSE(estimator_.GetAverageFps());
+}
+
+}  // namespace webrtc