diff --git a/website/queries/calcAge.php b/website/queries/calcAge.php
new file mode 100644
index 0000000..c2896b5
--- /dev/null
+++ b/website/queries/calcAge.php
@@ -0,0 +1,12 @@
+<?php
+/**
+ * calculates the age of a user
+ * @param string $bdayAsString
+ * @return int age
+ */
+function getAge(string $bdayAsString) : int {
+    $bday = new DateTime($bdayAsString);
+    $today = new DateTime("now");
+    $interval = $bday->diff($today);
+    return $interval->y;
+}
\ No newline at end of file