diff --git a/API-README b/API-README
index 951da26a..fe8f638c 100644
--- a/API-README
+++ b/API-README
@@ -461,6 +461,16 @@ miner.php - an example web page to access the API
 Feature Changelog for external applications using the API:
 
 
+API V1.28 (cgminer v3.3.4)
+
+Modified API commands:
+ 'devs', 'pga', 'asc', 'gpu' - add 'Device Hardware%' and 'Device Rejected%'
+ 'pools' - add 'Pool Rejected%' and 'Pool Stale%'
+ 'summary' - add 'Device Hardware%', 'Device Rejected%', 'Pool Rejected%',
+                 'Pool Stale%'
+
+----------
+
 API V1.27 (cgminer v3.3.2)
 
 Added API commands:
diff --git a/api.c b/api.c
index 073cc082..11215dd8 100644
--- a/api.c
+++ b/api.c
@@ -134,7 +134,7 @@ static const char SEPARATOR = '|';
 #define SEPSTR "|"
 static const char GPUSEP = ',';
 
-static const char *APIVERSION = "1.27";
+static const char *APIVERSION = "1.28";
 static const char *DEAD = "Dead";
 #if defined(HAVE_OPENCL) || defined(HAVE_AN_FPGA) || defined(HAVE_AN_ASIC)
 static const char *SICK = "Sick";
@@ -938,6 +938,7 @@ static struct api_data *api_add_data_full(struct api_data *root, char *name, enu
 			case API_FREQ:
 			case API_HS:
 			case API_DIFF:
+			case API_PERCENT:
 				api_data->data = (void *)malloc(sizeof(double));
 				*((double *)(api_data->data)) = *((double *)data);
 				break;
@@ -1069,6 +1070,11 @@ struct api_data *api_add_diff(struct api_data *root, char *name, double *data, b
 	return api_add_data_full(root, name, API_DIFF, (void *)data, copy_data);
 }
 
+struct api_data *api_add_percent(struct api_data *root, char *name, double *data, bool copy_data)
+{
+	return api_add_data_full(root, name, API_PERCENT, (void *)data, copy_data);
+}
+
 static struct api_data *print_data(struct api_data *root, char *buf, bool isjson, bool precom)
 {
 	struct api_data *tmp;
@@ -1161,6 +1167,9 @@ static struct api_data *print_data(struct api_data *root, char *buf, bool isjson
 			case API_TEMP:
 				sprintf(buf, "%.2f", *((float *)(root->data)));
 				break;
+			case API_PERCENT:
+				sprintf(buf, "%.4f", *((double *)(root->data)) * 100.0);
+				break;
 			default:
 				applog(LOG_ERR, "API: unknown2 data type %d ignored", root->type);
 				sprintf(buf, "%s%s%s", quote, UNKNOWN, quote);
@@ -1618,6 +1627,12 @@ static void gpustatus(struct io_data *io_data, int gpu, bool isjson, bool precom
 		root = api_add_diff(root, "Difficulty Rejected", &(cgpu->diff_rejected), false);
 		root = api_add_diff(root, "Last Share Difficulty", &(cgpu->last_share_diff), false);
 		root = api_add_time(root, "Last Valid Work", &(cgpu->last_device_valid_work), false);
+		double hwp = (cgpu->hw_errors + cgpu->diff1) ?
+				(double)(cgpu->hw_errors) / (double)(cgpu->hw_errors + cgpu->diff1) : 0;
+		root = api_add_percent(root, "Device Hardware%", &hwp, false);
+		double rejp = cgpu->diff1 ?
+				(double)(cgpu->diff_rejected) / (double)(cgpu->diff1) : 0;
+		root = api_add_percent(root, "Device Rejected%", &rejp, false);
 
 		root = print_data(root, buf, isjson, precom);
 		io_add(io_data, buf);
@@ -1691,6 +1706,12 @@ static void ascstatus(struct io_data *io_data, int asc, bool isjson, bool precom
 		root = api_add_bool(root, "No Device", &(cgpu->usbinfo.nodev), false);
 #endif
 		root = api_add_time(root, "Last Valid Work", &(cgpu->last_device_valid_work), false);
+		double hwp = (cgpu->hw_errors + cgpu->diff1) ?
+				(double)(cgpu->hw_errors) / (double)(cgpu->hw_errors + cgpu->diff1) : 0;
+		root = api_add_percent(root, "Device Hardware%", &hwp, false);
+		double rejp = cgpu->diff1 ?
+				(double)(cgpu->diff_rejected) / (double)(cgpu->diff1) : 0;
+		root = api_add_percent(root, "Device Rejected%", &rejp, false);
 
 		root = print_data(root, buf, isjson, precom);
 		io_add(io_data, buf);
@@ -1775,6 +1796,12 @@ static void pgastatus(struct io_data *io_data, int pga, bool isjson, bool precom
 		root = api_add_bool(root, "No Device", &(cgpu->usbinfo.nodev), false);
 #endif
 		root = api_add_time(root, "Last Valid Work", &(cgpu->last_device_valid_work), false);
+		double hwp = (cgpu->hw_errors + cgpu->diff1) ?
+				(double)(cgpu->hw_errors) / (double)(cgpu->hw_errors + cgpu->diff1) : 0;
+		root = api_add_percent(root, "Device Hardware%", &hwp, false);
+		double rejp = cgpu->diff1 ?
+				(double)(cgpu->diff_rejected) / (double)(cgpu->diff1) : 0;
+		root = api_add_percent(root, "Device Rejected%", &rejp, false);
 
 		root = print_data(root, buf, isjson, precom);
 		io_add(io_data, buf);
@@ -2145,6 +2172,12 @@ static void poolstatus(struct io_data *io_data, __maybe_unused SOCKETTYPE c, __m
 			root = api_add_const(root, "Stratum URL", BLANK, false);
 		root = api_add_bool(root, "Has GBT", &(pool->has_gbt), false);
 		root = api_add_uint64(root, "Best Share", &(pool->best_diff), true);
+		double rejp = (pool->diff_accepted + pool->diff_rejected + pool->diff_stale) ?
+				(double)(pool->diff_rejected) / (double)(pool->diff_accepted + pool->diff_rejected + pool->diff_stale) : 0;
+		root = api_add_percent(root, "Pool Rejected%", &rejp, false);
+		double stalep = (pool->diff_accepted + pool->diff_rejected + pool->diff_stale) ?
+				(double)(pool->diff_stale) / (double)(pool->diff_accepted + pool->diff_rejected + pool->diff_stale) : 0;
+		root = api_add_percent(root, "Pool Stale%", &stalep, false);
 
 		root = print_data(root, buf, isjson, isjson && (i > 0));
 		io_add(io_data, buf);
@@ -2191,6 +2224,18 @@ static void summary(struct io_data *io_data, __maybe_unused SOCKETTYPE c, __mayb
 	root = api_add_diff(root, "Difficulty Rejected", &(total_diff_rejected), true);
 	root = api_add_diff(root, "Difficulty Stale", &(total_diff_stale), true);
 	root = api_add_uint64(root, "Best Share", &(best_diff), true);
+	double hwp = (hw_errors + total_diff1) ?
+			(double)(hw_errors) / (double)(hw_errors + total_diff1) : 0;
+	root = api_add_percent(root, "Device Hardware%", &hwp, false);
+	double rejp = total_diff1 ?
+			(double)(total_diff_rejected) / (double)(total_diff1) : 0;
+	root = api_add_percent(root, "Device Rejected%", &rejp, false);
+	double prejp = (total_diff_accepted + total_diff_rejected + total_diff_stale) ?
+			(double)(total_diff_rejected) / (double)(total_diff_accepted + total_diff_rejected + total_diff_stale) : 0;
+	root = api_add_percent(root, "Pool Rejected%", &prejp, false);
+	double stalep = (total_diff_accepted + total_diff_rejected + total_diff_stale) ?
+			(double)(total_diff_stale) / (double)(total_diff_accepted + total_diff_rejected + total_diff_stale) : 0;
+	root = api_add_percent(root, "Pool Stale%", &stalep, false);
 
 	mutex_unlock(&hash_lock);
 
diff --git a/miner.h b/miner.h
index 74e7e769..e54db780 100644
--- a/miner.h
+++ b/miner.h
@@ -1387,7 +1387,8 @@ enum api_data_type {
 	API_FREQ,
 	API_VOLTS,
 	API_HS,
-	API_DIFF
+	API_DIFF,
+	API_PERCENT
 };
 
 struct api_data {
diff --git a/miner.php b/miner.php
index 10e52d14..f0f72d9d 100644
--- a/miner.php
+++ b/miner.php
@@ -764,7 +764,11 @@ function fmt($section, $name, $value, $when, $alldata)
 	case 'DEVS.Temperature':
 		$ret = $value.'°C';
 		if (!isset($alldata['GPU']))
+		{
+			if ($value == 0)
+				$ret = ' ';
 			break;
+		}
 	case 'GPU.GPU Clock':
 	case 'DEVS.GPU Clock':
 	case 'GPU.Memory Clock':
@@ -962,6 +966,23 @@ function fmt($section, $name, $value, $when, $alldata)
 		if ($value != '')
 			$ret = number_format((float)$value, 2);
 		break;
+	case 'DEVS.Device Hardware%':
+	case 'DEVS.Device Rejected%':
+	case 'ASC.Device Hardware%':
+	case 'ASC.Device Rejected%':
+	case 'PGA.Device Hardware%':
+	case 'PGA.Device Rejected%':
+	case 'GPU.Device Hardware%':
+	case 'GPU.Device Rejected%':
+	case 'POOL.Pool Rejected%':
+	case 'POOL.Pool Stale%':
+	case 'SUMMARY.Device Hardware%':
+	case 'SUMMARY.Device Rejected%':
+	case 'SUMMARY.Pool Rejected%':
+	case 'SUMMARY.Pool Stale%':
+		if ($value != '')
+			$ret = number_format((float)$value, 2) . '%';
+		break;
 	case 'SUMMARY.Best Share':
 		if ($value != '')
 			$ret = number_format((float)$value);