diff --git a/doc/quickref.1.in b/doc/quickref.1.in
index 823507f..ab54171 100644
--- a/doc/quickref.1.in
+++ b/doc/quickref.1.in
@@ -143,7 +143,7 @@ transfer.
 .TP
 .B \-a, \-\-average\-rate
 Turn the average rate counter on.  This will display the current average
-rate of data transfer (default: last 30s).
+rate of data transfer (default: last 30s, see --eta-window).
 .TP
 .B \-b, \-\-bytes
 Turn the total byte counter on.  This will display the total amount of
@@ -265,6 +265,11 @@ Wait
 seconds between updates.  The default is to update every second.
 Note that this can be a decimal such as 0.1.
 .TP
+.B \-m SEC, \-\-eta-window SEC
+Compute current average rate over a
+.B SEC
+seconds window for ETA calculation (default 30s).
+.TP
 .B \-w WIDTH, \-\-width WIDTH
 Assume the terminal is
 .B WIDTH
diff --git a/src/include/options.h b/src/include/options.h
index 90d8f85..9de9e68 100644
--- a/src/include/options.h
+++ b/src/include/options.h
@@ -42,6 +42,7 @@ struct opts_s {           /* structure describing run-time options */
 	double delay_start;            /* delay before first display */
 	unsigned int watch_pid;	       /* process to watch fds of */
 	int watch_fd;		       /* fd to watch */
+	unsigned int eta_window;       /* time window in seconds for eta calculations */
 	unsigned int width;            /* screen width */
 	unsigned int height;           /* screen height */
 	char *name;                    /* process name, if any */
diff --git a/src/include/pv.h b/src/include/pv.h
index cde7d08..26130e9 100644
--- a/src/include/pv.h
+++ b/src/include/pv.h
@@ -93,6 +93,7 @@ extern void pv_state_name_set(pvstate_t, const char *);
 extern void pv_state_format_string_set(pvstate_t, const char *);
 extern void pv_state_watch_pid_set(pvstate_t, unsigned int);
 extern void pv_state_watch_fd_set(pvstate_t, int);
+extern void pv_state_eta_window_set(pvstate_t, int);
 
 extern void pv_state_inputfiles(pvstate_t, int, const char **);
 
diff --git a/src/main/help.c b/src/main/help.c
index 2ebab41..7d9da6f 100644
--- a/src/main/help.c
+++ b/src/main/help.c
@@ -40,6 +40,8 @@ void display_help(void)
 		 N_("show data transfer rate counter")},
 		{"-a", "--average-rate", 0,
 		 N_("show data transfer average rate counter")},
+		{"-m", "--eta-window", N_("SEC"),
+		 N_("compute current average rate over a SEC seconds window for ETA (default 30s)")},
 		{"-b", "--bytes", 0,
 		 N_("show number of bytes transferred")},
 		{"-T", "--buffer-percent", 0,
diff --git a/src/main/main.c b/src/main/main.c
index 75fbae2..5e0f75f 100644
--- a/src/main/main.c
+++ b/src/main/main.c
@@ -206,6 +206,7 @@ int main(int argc, char **argv)
 	pv_state_format_string_set(state, opts->format);
 	pv_state_watch_pid_set(state, opts->watch_pid);
 	pv_state_watch_fd_set(state, opts->watch_fd);
+	pv_state_eta_window_set(state, opts->eta_window);
 
 	pv_state_set_format(state, opts->progress, opts->timer, opts->eta,
 			    opts->fineta, opts->rate, opts->average_rate,
diff --git a/src/main/options.c b/src/main/options.c
index 0d370ed..35e501d 100644
--- a/src/main/options.c
+++ b/src/main/options.c
@@ -80,12 +80,13 @@ opts_t opts_parse(int argc, char **argv)
 		{"remote", 1, NULL, (int) 'R'},
 		{"pidfile", 1, NULL, (int) 'P'},
 		{"watchfd", 1, NULL, (int) 'd'},
+		{"eta-window", 1, NULL, (int) 'm'},
 		{NULL, 0, NULL, 0}
 	};
 	int option_index = 0;
 #endif
 	char *short_options =
-	    "hVpteIrabTA:fnqcWD:s:l0i:w:H:N:F:L:B:CESR:P:d:";
+	    "hVpteIrabTA:fnqcWD:s:l0i:w:H:N:F:L:B:CESR:P:d:m:";
 	int c, numopts;
 	unsigned int check_pid;
 	int check_fd;
@@ -121,6 +122,7 @@ opts_t opts_parse(int argc, char **argv)
 	opts->delay_start = 0;
 	opts->watch_pid = 0;
 	opts->watch_fd = -1;
+	opts->eta_window = 30;
 
 	do {
 #ifdef HAVE_GETOPT_LONG
@@ -144,6 +146,7 @@ opts_t opts_parse(int argc, char **argv)
 		case 'L':
 		case 'B':
 		case 'R':
+		case 'm':
 			if (pv_getnum_check(optarg, PV_NUMTYPE_INTEGER) !=
 			    0) {
 				fprintf(stderr, "%s: -%c: %s\n",
@@ -310,6 +313,9 @@ opts_t opts_parse(int argc, char **argv)
 			(void) sscanf(optarg, "%u:%d", &(opts->watch_pid),
 				      &(opts->watch_fd));
 			break;
+		case 'm':
+			opts->eta_window = pv_getnum_ui(optarg);
+			break;
 		default:
 #ifdef HAVE_GETOPT_LONG
 			fprintf(stderr,
diff --git a/src/pv/state.c b/src/pv/state.c
index ed9ff7f..96c27b7 100644
--- a/src/pv/state.c
+++ b/src/pv/state.c
@@ -51,10 +51,6 @@ pvstate_t pv_state_alloc(const char *program_name)
 #endif				/* HAVE_SPLICE */
 	state->display_visible = false;
 
-	state->history_len = 30+1;  /* default history for current avg rate */
-	state->history_interval = 1;
-	pv_alloc_history(state);
-
 	return state;
 }
 
@@ -234,6 +230,19 @@ void pv_state_watch_fd_set(pvstate_t state, int val)
 	state->watch_fd = val;
 };
 
+void pv_state_eta_window_set(pvstate_t state, int val)
+{
+	if (val >= 20) {
+		state->history_len = val / 5 + 1;
+		state->history_interval = 5;
+	}
+	else {
+		state->history_len = val + 1;
+		state->history_interval = 1;
+	}
+	pv_alloc_history(state);
+};
+
 
 /*
  * Set the array of input files.