diff --git a/src/commit_templater.rs b/src/commit_templater.rs
index 7dc1374a1..507024948 100644
--- a/src/commit_templater.rs
+++ b/src/commit_templater.rs
@@ -382,6 +382,21 @@ impl Template<()> for ShortestIdPrefix {
     }
 }
 
+impl ShortestIdPrefix {
+    fn to_upper(&self) -> Self {
+        Self {
+            prefix: self.prefix.to_ascii_uppercase(),
+            rest: self.rest.to_ascii_uppercase(),
+        }
+    }
+    fn to_lower(&self) -> Self {
+        Self {
+            prefix: self.prefix.to_ascii_lowercase(),
+            rest: self.rest.to_ascii_lowercase(),
+        }
+    }
+}
+
 fn build_shortest_id_prefix_method<'repo>(
     language: &CommitTemplateLanguage<'repo, '_>,
     self_property: impl TemplateProperty<Commit, Output = ShortestIdPrefix> + 'repo,
@@ -402,6 +417,20 @@ fn build_shortest_id_prefix_method<'repo>(
                 TemplatePropertyFn(|id: &ShortestIdPrefix| id.rest.clone()),
             ))
         }
+        "upper" => {
+            template_parser::expect_no_arguments(function)?;
+            language.wrap_shortest_id_prefix(template_parser::chain_properties(
+                self_property,
+                TemplatePropertyFn(|id: &ShortestIdPrefix| id.to_upper()),
+            ))
+        }
+        "lower" => {
+            template_parser::expect_no_arguments(function)?;
+            language.wrap_shortest_id_prefix(template_parser::chain_properties(
+                self_property,
+                TemplatePropertyFn(|id: &ShortestIdPrefix| id.to_lower()),
+            ))
+        }
         _ => {
             return Err(TemplateParseError::no_such_method(
                 "ShortestIdPrefix",
diff --git a/src/template_parser.rs b/src/template_parser.rs
index ad032e6e4..e7e752fad 100644
--- a/src/template_parser.rs
+++ b/src/template_parser.rs
@@ -906,6 +906,20 @@ fn build_string_method<'a, L: TemplateLanguage<'a>>(
                 TemplatePropertyFn(|s: &String| s.lines().next().unwrap_or_default().to_string()),
             ))
         }
+        "upper" => {
+            expect_no_arguments(function)?;
+            language.wrap_string(chain_properties(
+                self_property,
+                TemplatePropertyFn(|s: &String| s.to_uppercase()),
+            ))
+        }
+        "lower" => {
+            expect_no_arguments(function)?;
+            language.wrap_string(chain_properties(
+                self_property,
+                TemplatePropertyFn(|s: &String| s.to_lowercase()),
+            ))
+        }
         _ => return Err(TemplateParseError::no_such_method("String", function)),
     };
     Ok(property)
diff --git a/tests/test_templater.rs b/tests/test_templater.rs
index 93f7e739f..09143ad69 100644
--- a/tests/test_templater.rs
+++ b/tests/test_templater.rs
@@ -388,6 +388,20 @@ fn test_templater_separate_function() {
         render(r#"separate(author, "X", "Y", "Z")"#), @"X <>Y <>Z");
 }
 
+#[test]
+fn test_templater_upper_lower() {
+    let test_env = TestEnvironment::default();
+    test_env.jj_cmd_success(test_env.env_root(), &["init", "repo", "--git"]);
+    let repo_path = test_env.env_root().join("repo");
+    let render = |template| get_colored_template_output(&test_env, &repo_path, "@-", template);
+
+    insta::assert_snapshot!(
+      render(r#"change_id.shortest(4).upper() change_id.shortest(4).upper().lower()"#),
+      @"ZZZZzzzz");
+    insta::assert_snapshot!(
+      render(r#""Hello".upper() "Hello".lower()"#), @"HELLOhello");
+}
+
 #[test]
 fn test_templater_alias() {
     let test_env = TestEnvironment::default();