diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1b36d3c38..358284c98 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,7 @@
 
 ## unreleased
 
+* [CHANGE] Notifier: Increment the prometheus_notifications_errors_total metric by the number of affected alerts rather than by one per batch of affected alerts. #15428
 * [ENHANCEMENT] OTLP receiver: Convert also metric metadata. #15416
 
 ## 3.0.0 / 2024-11-14
diff --git a/documentation/prometheus-mixin/alerts.libsonnet b/documentation/prometheus-mixin/alerts.libsonnet
index 563daab80..9a6de90d8 100644
--- a/documentation/prometheus-mixin/alerts.libsonnet
+++ b/documentation/prometheus-mixin/alerts.libsonnet
@@ -84,8 +84,8 @@
               severity: 'warning',
             },
             annotations: {
-              summary: 'Prometheus has encountered more than 1% errors sending alerts to a specific Alertmanager.',
-              description: '{{ printf "%%.1f" $value }}%% errors while sending alerts from Prometheus %(prometheusName)s to Alertmanager {{$labels.alertmanager}}.' % $._config,
+              summary: 'More than 1% of alerts sent by Prometheus to a specific Alertmanager were affected by errors.',
+              description: '{{ printf "%%.1f" $value }}%% of alerts sent by Prometheus %(prometheusName)s to Alertmanager {{$labels.alertmanager}} were affected by errors.' % $._config,
             },
           },
           {
diff --git a/notifier/notifier.go b/notifier/notifier.go
index 09a2005a3..956fd4652 100644
--- a/notifier/notifier.go
+++ b/notifier/notifier.go
@@ -160,7 +160,7 @@ func newAlertMetrics(r prometheus.Registerer, queueCap int, queueLen, alertmanag
 			Namespace: namespace,
 			Subsystem: subsystem,
 			Name:      "errors_total",
-			Help:      "Total number of errors sending alert notifications.",
+			Help:      "Total number of sent alerts affected by errors.",
 		},
 			[]string{alertmanagerLabel},
 		),
@@ -619,13 +619,13 @@ func (n *Manager) sendAll(alerts ...*Alert) bool {
 
 			go func(ctx context.Context, client *http.Client, url string, payload []byte, count int) {
 				if err := n.sendOne(ctx, client, url, payload); err != nil {
-					n.logger.Error("Error sending alert", "alertmanager", url, "count", count, "err", err)
-					n.metrics.errors.WithLabelValues(url).Inc()
+					n.logger.Error("Error sending alerts", "alertmanager", url, "count", count, "err", err)
+					n.metrics.errors.WithLabelValues(url).Add(float64(count))
 				} else {
 					numSuccess.Inc()
 				}
 				n.metrics.latency.WithLabelValues(url).Observe(time.Since(begin).Seconds())
-				n.metrics.sent.WithLabelValues(url).Add(float64(len(amAlerts)))
+				n.metrics.sent.WithLabelValues(url).Add(float64(count))
 
 				wg.Done()
 			}(ctx, ams.client, am.url().String(), payload, len(amAlerts))