diff --git a/src/main/resources/templates/calculator.html b/src/main/resources/templates/calculator.html
index 71233a1..379ea9d 100644
--- a/src/main/resources/templates/calculator.html
+++ b/src/main/resources/templates/calculator.html
@@ -1,5 +1,5 @@
 <!DOCTYPE html>
-<html xmlns:th="http://www.thymeleaf.org" lang="en">
+<html xmlns:th="http://www.thymeleaf.org" lang="de">
 <head>
     <meta charset="UTF-8">
     <meta name="viewport" content="width=device-width, initial-scale=1.0">
