diff --git a/src/fix_countdown.cpp b/src/fix_countdown.cpp
new file mode 100644
index 0000000000..1687fea37c
--- /dev/null
+++ b/src/fix_countdown.cpp
@@ -0,0 +1,151 @@
+/* ----------------------------------------------------------------------
+   LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
+   http://lammps.sandia.gov, Sandia National Laboratories
+   Steve Plimpton, sjplimp@sandia.gov
+
+   Copyright (2003) Sandia Corporation.  Under the terms of Contract
+   DE-AC04-94AL85000 with Sandia Corporation, the U.S. Government retains
+   certain rights in this software.  This software is distributed under
+   the GNU General Public License.
+
+   See the README file in the top-level LAMMPS directory.
+------------------------------------------------------------------------- */
+
+/* ----------------------------------------------------------------------
+   Contributing author: Axel Kohlmeyer (Temple U)
+------------------------------------------------------------------------- */
+
+#include "fix_countdown.h"
+#include "comm.h"
+#include "error.h"
+#include "force.h"
+#include "memory.h"
+#include "update.h"
+
+#include <math.h>
+
+using namespace LAMMPS_NS;
+using namespace FixConst;
+
+static const double decay = 0.999;
+static const int maxtimes = 1000;
+
+/* ---------------------------------------------------------------------- */
+
+FixCountdown::FixCountdown(LAMMPS *lmp, int narg, char **arg) :
+  Fix(lmp, narg, arg)
+{
+  scalar_flag = 1;
+  extscalar = 0;
+  vector_flag = 1;
+  size_vector = 4;
+  nevery = 1;
+
+  _times = NULL;
+  _last_wall = _complete = 0.0;
+  _outfreq = 0;
+  _ntimes = _idx = 0;
+
+  printf("narg=%d arg[0]=%s arg[1]=%s arg[2]=%s arg[3]=%s\n",
+   narg,arg[0],arg[1],arg[2],arg[3]);
+  if (narg == 4) {
+    _outfreq = force->inumeric(FLERR,arg[3]);
+  } else error->all(FLERR,"Illegal fix countdown command");
+  printf("outfreq=%d\n",_outfreq);
+}
+
+/* ---------------------------------------------------------------------- */
+
+FixCountdown::~FixCountdown()
+{
+  memory->destroy(_times);
+}
+
+/* ---------------------------------------------------------------------- */
+
+int FixCountdown::setmask()
+{
+  int mask = 0;
+  mask |= END_OF_STEP;
+  return mask;
+}
+
+/* ---------------------------------------------------------------------- */
+
+void FixCountdown::setup(int vflag)
+{
+  if (_times == NULL) {
+    memory->create(_times,maxtimes,"countdown:times");
+  }
+  _ntimes = _idx = 0;
+  _last_wall = MPI_Wtime();
+  _complete = 0.0;
+  _eta[0] = _eta[1] = _eta[2] = _eta[3] = 0.0;
+}
+
+/* ---------------------------------------------------------------------- */
+
+void FixCountdown::end_of_step()
+{
+  const double wtime = MPI_Wtime();
+  const double delta = wtime - _last_wall;
+  const double tstep = static_cast<double>(update->laststep-update->firststep); 
+
+  _last_wall = wtime;
+  _times[_idx++] = delta;
+  if (_ntimes < maxtimes) ++_ntimes;
+  if (_idx == maxtimes) _idx = 0; 
+  _complete = static_cast<double>(update->ntimestep-update->firststep)/tstep; 
+
+  double tsum = 0.0;
+  double wsum = 0.0;
+  double w = 1.0;
+  int i,j;
+
+  // compute weighted average of time per timestep
+  for (i=_idx; i < _idx+_ntimes; ++i) {
+    j = (i < _ntimes) ? i : i - _ntimes;
+    tsum += w*_times[j];
+    wsum += w;
+    w *= decay;
+  }
+  w = tsum/wsum * tstep * (1.0 - _complete);
+  int day = floor(w/86400.0);
+  _eta[0] = static_cast<double>(day);
+  w -= _eta[0]*86400.0;
+  int hrs = floor(w/3600.0);
+  _eta[1] = static_cast<double>(hrs);
+  w -= _eta[1]*3600.0;
+  int min = floor(w/60.0);
+  _eta[2] = static_cast<double>(min);
+  w -= _eta[2]*60.0;
+  _eta[3] = w;
+
+  if (_outfreq > 0) {
+    if ((update->ntimestep % _outfreq == 0) && (comm->me == 0)) {
+      const char fmt[] = " %6.2f%% complete. "
+         "Estimated time to completion: %dd %02dh %02dm %04.2fs\n";
+      if (screen) fprintf(screen,fmt,_complete*100.0,day,hrs,min,w);
+      if (logfile) fprintf(logfile,fmt,_complete*100.0,day,hrs,min,w);
+    }
+  }
+}
+
+/* ----------------------------------------------------------------------
+   return completion fraction
+------------------------------------------------------------------------- */
+
+double FixCountdown::compute_scalar()
+{
+  return _complete;
+}
+
+/* ----------------------------------------------------------------------
+   return estimated time to completion component
+------------------------------------------------------------------------- */
+
+double FixCountdown::compute_vector(int id)
+{
+  return _eta[id];
+}
+
diff --git a/src/fix_countdown.h b/src/fix_countdown.h
new file mode 100644
index 0000000000..5d03b0e4a5
--- /dev/null
+++ b/src/fix_countdown.h
@@ -0,0 +1,48 @@
+/* -*- c++ -*- ----------------------------------------------------------
+   LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
+   http://lammps.sandia.gov, Sandia National Laboratories
+   Steve Plimpton, sjplimp@sandia.gov
+
+   Copyright (2003) Sandia Corporation.  Under the terms of Contract
+   DE-AC04-94AL85000 with Sandia Corporation, the U.S. Government retains
+   certain rights in this software.  This software is distributed under
+   the GNU General Public License.
+
+   See the README file in the top-level LAMMPS directory.
+------------------------------------------------------------------------- */
+
+#ifdef FIX_CLASS
+
+FixStyle(countdown,FixCountdown)
+
+#else
+
+#ifndef LMP_FIX_COUNTDOWN_H
+#define LMP_FIX_COUNTDOWN_H
+
+#include "fix.h"
+
+namespace LAMMPS_NS {
+
+class FixCountdown : public Fix {
+ public:
+  FixCountdown(class LAMMPS *, int, char **);
+  ~FixCountdown();
+  int setmask();
+  void setup(int);
+  void end_of_step();
+  double compute_scalar();
+  double compute_vector(int);
+
+ private:
+  double *_times;                // list of times per time step
+  double _last_wall, _complete;  // last wall time; completion fraction
+  double _eta[4];                // estimated time: days, hours, mins, secs
+  bigint _outfreq;               // output frequency
+  int    _ntimes, _idx;          // number of recorded times, index in array
+};
+
+}
+
+#endif
+#endif