diff --git a/spring-boot-project/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/metrics/web/servlet/WebMvcTags.java b/spring-boot-project/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/metrics/web/servlet/WebMvcTags.java
index 477d7b422760..89c6d1ba3f6c 100644
--- a/spring-boot-project/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/metrics/web/servlet/WebMvcTags.java
+++ b/spring-boot-project/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/metrics/web/servlet/WebMvcTags.java
@@ -175,22 +175,21 @@ public static Tag exception(Throwable exception) {
 	 */
 	public static Tag outcome(HttpServletResponse response) {
 		if (response != null) {
-			HttpStatus status = extractStatus(response);
-			if (status != null) {
-				if (status.is1xxInformational()) {
+			HttpStatus.Series series = HttpStatus.Series.resolve(response.getStatus());
+			if (series != null) {
+				switch (series) {
+				case INFORMATIONAL:
 					return OUTCOME_INFORMATIONAL;
-				}
-				if (status.is2xxSuccessful()) {
+				case SUCCESSFUL:
 					return OUTCOME_SUCCESS;
-				}
-				if (status.is3xxRedirection()) {
+				case REDIRECTION:
 					return OUTCOME_REDIRECTION;
-				}
-				if (status.is4xxClientError()) {
+				case CLIENT_ERROR:
 					return OUTCOME_CLIENT_ERROR;
+				case SERVER_ERROR:
+					return OUTCOME_SERVER_ERROR;
 				}
 			}
-			return OUTCOME_SERVER_ERROR;
 		}
 		return OUTCOME_UNKNOWN;
 	}
diff --git a/spring-boot-project/spring-boot-actuator/src/test/java/org/springframework/boot/actuate/endpoint/web/servlet/WebMvcTagsTests.java b/spring-boot-project/spring-boot-actuator/src/test/java/org/springframework/boot/actuate/endpoint/web/servlet/WebMvcTagsTests.java
index 4125ca31c8ac..55e27a6b913d 100644
--- a/spring-boot-project/spring-boot-actuator/src/test/java/org/springframework/boot/actuate/endpoint/web/servlet/WebMvcTagsTests.java
+++ b/spring-boot-project/spring-boot-actuator/src/test/java/org/springframework/boot/actuate/endpoint/web/servlet/WebMvcTagsTests.java
@@ -136,6 +136,13 @@ void outcomeTagIsClientErrorWhenResponseIs4xx() {
 		assertThat(tag.getValue()).isEqualTo("CLIENT_ERROR");
 	}
 
+	@Test
+	void outcomeTagIsClientErrorWhenResponseIsNonStandardInClientSeries() {
+		this.response.setStatus(490);
+		Tag tag = WebMvcTags.outcome(this.response);
+		assertThat(tag.getValue()).isEqualTo("CLIENT_ERROR");
+	}
+
 	@Test
 	void outcomeTagIsServerErrorWhenResponseIs5xx() {
 		this.response.setStatus(500);
@@ -143,4 +150,11 @@ void outcomeTagIsServerErrorWhenResponseIs5xx() {
 		assertThat(tag.getValue()).isEqualTo("SERVER_ERROR");
 	}
 
+	@Test
+	void outcomeTagIsUnknownWhenResponseStatusIsInUnknownSeries() {
+		this.response.setStatus(701);
+		Tag tag = WebMvcTags.outcome(this.response);
+		assertThat(tag.getValue()).isEqualTo("UNKNOWN");
+	}
+
 }