diff --git a/bindings/python/src/encoding.rs b/bindings/python/src/encoding.rs
index 3056c371..7da839e7 100644
--- a/bindings/python/src/encoding.rs
+++ b/bindings/python/src/encoding.rs
@@ -4,7 +4,7 @@ use crate::error::PyError;
 use pyo3::exceptions;
 use pyo3::prelude::*;
 use pyo3::types::*;
-use pyo3::{PyMappingProtocol, PyObjectProtocol};
+use pyo3::{PyMappingProtocol, PyObjectProtocol, PySequenceProtocol};
 use tk::tokenizer::PaddingDirection;
 
 fn get_range(item: PyObject, max_len: usize) -> PyResult<std::ops::Range<usize>> {
@@ -133,6 +133,13 @@ impl PyObjectProtocol for Encoding {
     }
 }
 
+#[pyproto]
+impl PySequenceProtocol for Encoding {
+    fn __len__(self) -> PyResult<usize> {
+        Ok(self.encoding.get_ids().len())
+    }
+}
+
 #[pymethods]
 impl Encoding {
     #[getter]