diff --git a/tests/test_string.py b/tests/test_string.py
index b13a8f8..4228ddb 100644
--- a/tests/test_string.py
+++ b/tests/test_string.py
@@ -28,6 +28,12 @@
             [True, False, True, False],
             {"elem": "num"},
         ),
+        (
+            "str_len",
+            ["num", "1num", "", "*", " ", "sp ace", "ta	b"],
+            [3, 4, 0, 1, 1, 6, 4],
+            {}
+        )
     ],
 )
 def test_methods_with_args(
diff --git a/ulist/python/ulist/core.py b/ulist/python/ulist/core.py
index dc2f14a..a3d53e8 100644
--- a/ulist/python/ulist/core.py
+++ b/ulist/python/ulist/core.py
@@ -446,6 +446,11 @@ def starts_with(self, elem: str) -> UltraFastList:
         assert isinstance(self._values, StringList)
         return UltraFastList(self._values.starts_with(elem))
 
+    def str_len(self) -> "UltraFastList":
+        """Return each element's string length of self."""
+        assert isinstance(self._values, StringList)
+        return UltraFastList(self._values.str_len())
+
     def sub(self, other: "UltraFastList") -> "UltraFastList":
         """Return self - other."""
         assert not isinstance(self._values, (BooleanList, StringList))
diff --git a/ulist/python/ulist/ulist.pyi b/ulist/python/ulist/ulist.pyi
index 3ca9637..6620702 100644
--- a/ulist/python/ulist/ulist.pyi
+++ b/ulist/python/ulist/ulist.pyi
@@ -264,6 +264,7 @@ class StringList:
     def size(self) -> int: ...
     def sort(self, ascending: bool) -> StringList: ...
     def starts_with(self, elem: str) -> BooleanList: ...
+    def str_len(self) -> IntegerList64: ...
     def to_list(self) -> List[str]: ...
     def union_all(self, other: LIST_RS) -> LIST_RS: ...
     def unique(self) -> StringList: ...
diff --git a/ulist/src/string.rs b/ulist/src/string.rs
index 0e456aa..c05021f 100644
--- a/ulist/src/string.rs
+++ b/ulist/src/string.rs
@@ -129,6 +129,11 @@ impl StringList {
         BooleanList::new(vec)
     }
 
+    pub fn str_len(&self) -> IntegerList64 {
+        let vec = self.values().iter().map(|x| x.len() as i64).collect();
+        IntegerList64::new(vec)
+    }
+
     pub fn to_list(&self) -> Vec<String> {
         List::to_list(self)
     }