diff --git a/includes/functions.php b/includes/functions.php
index 3ed1a4a..2d18377 100644
--- a/includes/functions.php
+++ b/includes/functions.php
@@ -69,16 +69,3 @@ function listPath(
     . '.json';
 }
 
-function calculateNextInterval(array $word, bool $correct): int
-{
-    $correctCount = $word['correct'] ?? 0;
-
-    if (!$correct) {
-        return 1;
-    }
-
-    // gecontroleerde groei (SM-lite)
-    $interval = 1 + ($correctCount * 2);
-
-    return min(30, $interval);
-}
\ No newline at end of file