diff --git a/README.md b/README.md
index 7fd6b40..f51bd84 100644
--- a/README.md
+++ b/README.md
@@ -64,6 +64,10 @@ Which would be enough to tell sanoid to take and keep 36 hourly snapshots, 30 da
 
 	This option is designed to be run by a Nagios monitoring system. It reports on the health of the zpool your filesystems are on. It only monitors filesystems that are configured in the sanoid.conf file.
 
++ --monitor-capacity
+
+	This option is designed to be run by a Nagios monitoring system. It reports on the capacity of the zpool your filesystems are on. It only monitors pools that are configured in the sanoid.conf file.
+
 + --force-update
 
 	This clears out sanoid's zfs snapshot listing cache. This is normally not needed.
diff --git a/sanoid b/sanoid
index c07e090..d0800e6 100755
--- a/sanoid
+++ b/sanoid
@@ -18,7 +18,8 @@ use Time::Local;      # to parse dates in reverse
 my %args = ("configdir" => "/etc/sanoid");
 GetOptions(\%args, "verbose", "debug", "cron", "readonly", "quiet",
                    "monitor-health", "force-update", "configdir=s",
-                   "monitor-snapshots", "take-snapshots", "prune-snapshots"
+                   "monitor-snapshots", "take-snapshots", "prune-snapshots",
+                   "monitor-capacity"
           ) or pod2usage(2);
 
 # If only config directory (or nothing) has been specified, default to --cron --verbose
@@ -52,6 +53,7 @@ my @params = ( \%config, \%snaps, \%snapsbytype, \%snapsbypath );
 if ($args{'debug'})		{ $args{'verbose'}=1; blabber (@params); }
 if ($args{'monitor-snapshots'}) { monitor_snapshots(@params); }
 if ($args{'monitor-health'}) 	{ monitor_health(@params); }
+if ($args{'monitor-capacity'})  { monitor_capacity(@params); }
 if ($args{'force-update'}) 	{ my $snaps = getsnaps( \%config, $cacheTTL, 1 ); }
 
 if ($args{'cron'}) {
@@ -174,6 +176,61 @@ sub monitor_snapshots {
 	exit $errorlevel;
 }
 
+
+####################################################################################
+####################################################################################
+####################################################################################
+
+sub monitor_capacity {
+	my ($config, $snaps, $snapsbytype, $snapsbypath) = @_;
+	my %pools;
+	my @messages;
+	my $errlevel=0;
+
+	# build pool list with corresponding capacity limits
+	foreach my $section (keys %config) {
+		my @pool = split ('/',$section);
+
+		if (scalar @pool == 1 || !defined($pools{$pool[0]}) ) {
+			my %capacitylimits;
+
+			if (!check_capacity_limit($config{$section}{'capacity_warn'})) {
+				die "ERROR: invalid zpool capacity warning limit!\n";
+			}
+
+			if ($config{$section}{'capacity_warn'} != 0) {
+				$capacitylimits{'warn'} = $config{$section}{'capacity_warn'};
+			}
+
+			if (!check_capacity_limit($config{$section}{'capacity_crit'})) {
+				die "ERROR: invalid zpool capacity critical limit!\n";
+			}
+
+			if ($config{$section}{'capacity_crit'} != 0) {
+				$capacitylimits{'crit'} = $config{$section}{'capacity_crit'};
+			}
+
+			if (%capacitylimits) {
+				$pools{$pool[0]} = \%capacitylimits;
+			}
+		}
+	}
+
+	foreach my $pool (keys %pools) {
+		my $capacitylimitsref = $pools{$pool};
+
+		my ($exitcode, $msg) = check_zpool_capacity($pool,\%$capacitylimitsref);
+		if ($exitcode > $errlevel) { $errlevel = $exitcode; }
+		chomp $msg;
+		push (@messages, $msg);
+	}
+
+	my @warninglevels = ('','*** WARNING *** ','*** CRITICAL *** ');
+	my $message = $warninglevels[$errlevel] . join (', ',@messages);
+	print "$message\n";
+	exit $errlevel;
+}
+
 ####################################################################################
 ####################################################################################
 ####################################################################################
@@ -900,6 +957,74 @@ sub check_zpool() {
 	return ($ERRORS{$state},$msg);
 } # end check_zpool()
 
+sub check_capacity_limit() {
+	my $value = shift;
+
+	if (!defined($value) || $value !~ /^\d+\z/) {
+		return undef;
+	}
+
+	if ($value < 0 || $value > 100) {
+		return undef;
+	}
+
+	return 1
+}
+
+sub check_zpool_capacity() {
+	my %ERRORS=('DEPENDENT'=>4,'UNKNOWN'=>3,'OK'=>0,'WARNING'=>1,'CRITICAL'=>2);
+	my $state="UNKNOWN";
+	my $msg="FAILURE";
+
+	my $pool=shift;
+	my $capacitylimitsref=shift;
+	my %capacitylimits=%$capacitylimitsref;
+
+	my $statcommand="/sbin/zpool list -H -o cap $pool";
+
+	if (! open STAT, "$statcommand|") {
+		print ("$state '$statcommand' command returns no result!\n");
+		exit $ERRORS{$state};
+	}
+
+	my $line = <STAT>;
+	close(STAT);
+
+	chomp $line;
+	my @row = split(/ +/, $line);
+	my $cap=$row[0];
+
+	## check for valid capacity value
+	if ($cap !~ m/^[0-9]{1,3}%$/ ) {
+		$state = "CRITICAL";
+		$msg = sprintf "ZPOOL {%s} does not exist and/or is not responding!\n", $pool;
+		print $state, " ", $msg;
+		exit ($ERRORS{$state});
+	}
+
+	$state="OK";
+
+	# check capacity
+	my $capn = $cap;
+	$capn =~ s/\D//g;
+
+	if (defined($capacitylimits{"warn"})) {
+		if ($capn >= $capacitylimits{"warn"}) {
+			$state = "WARNING";
+		}
+	}
+
+	if (defined($capacitylimits{"crit"})) {
+		if ($capn >= $capacitylimits{"crit"}) {
+			$state = "CRITICAL";
+		}
+	}
+
+	$msg = sprintf "ZPOOL %s : %s\n", $pool, $cap;
+	$msg = "$state $msg";
+	return ($ERRORS{$state},$msg);
+} # end check_zpool_capacity()
+
 ######################################################################################################
 ######################################################################################################
 ######################################################################################################
@@ -1079,6 +1204,7 @@ Options:
   --force-update        Clears out sanoid's zfs snapshot cache
 
   --monitor-health      Reports on zpool "health", in a Nagios compatible format
+  --monitor-capacity    Reports on zpool capacity, in a Nagios compatible format
   --monitor-snapshots   Reports on snapshot "health", in a Nagios compatible format
   --take-snapshots      Creates snapshots as specified in sanoid.conf
   --prune-snapshots     Purges expired snapshots as specified in sanoid.conf
diff --git a/sanoid.defaults.conf b/sanoid.defaults.conf
index 35c804d..d86cc47 100644
--- a/sanoid.defaults.conf
+++ b/sanoid.defaults.conf
@@ -70,3 +70,7 @@ monthly_warn = 32
 monthly_crit = 35
 yearly_warn = 0
 yearly_crit = 0
+
+# default limits for capacity checks (if set to 0, limit will not be checked)
+capacity_warn = 80
+capacity_crit = 95