diff --git a/www/index.php b/www/index.php
index bddbf60..12c3e9a 100644
--- a/www/index.php
+++ b/www/index.php
@@ -91,15 +91,18 @@ if ($path == '') {
 
     if ($format === 'text') {
         header('Content-Type: text/plain; charset=UTF-8');
-        foreach ($clients as $c)
-            echo "$c\n";
+        foreach ($clients as $c) {
+            $size = intval(exec("du -s .data/$c"));
+            echo "$c ($size kB)\n";
+        }
     } else if ($format === 'json') {
         header('Content-Type: application/json; charset=UTF-8');
         echo "{\"data\": [";
         $first = true;
         foreach ($clients as $c) {
             if (!$first) echo ",";
-            echo "\n  {\"name\": \"$c\"}";
+            $size = intval(exec("du -s .data/$c")) * 1024;
+            echo "\n  {\"name\": \"$c\", \"used_space\": $size}";
             $first = false;
         }
         echo "\n]}\n";
@@ -122,10 +125,11 @@ if ($path == '') {
                 <h3>Mandanten</h3>
                 <p class="center"><a href="https://elwig.at/">Homepage</a></p>
                 <table>
-                    <thead><tr><th>Name</th></tr></thead>
+                    <thead><tr><th>Name</th><th>Used</th></tr></thead>
                     <tbody>
                     <?php foreach ($clients as $c) {
-                        echo "          <tr><td><a href='$c'>$c</a></td></tr>\n";
+                        $size = intval(exec("du -s .data/$c"));
+                        echo "          <tr><td><a href='$c'>$c</a></td><td class='right'>$size kB</td></tr>\n";
                     } ?>
                     </tbody>
                 </table>
@@ -159,7 +163,8 @@ foreach ($clients as $c) {
         }
 
         header('Content-Type: application/json; charset=UTF-8');
-        echo "{\"data\": [\n";
+        $size = intval(exec("du -s .data/$c")) * 1024;
+        echo "{\"used_space\": $size, \"data\": [\n";
         $first = true;
         foreach (scandir(".data/$c/") as $file) {
             if (str_starts_with($file, ".") || str_ends_with($file, ".php") || str_ends_with($file, ".inc")) continue;
diff --git a/www/res/style.css b/www/res/style.css
index a07ea01..d14884d 100644
--- a/www/res/style.css
+++ b/www/res/style.css
@@ -154,6 +154,10 @@ main section h3 {
     text-align: center;
 }
 
+.right {
+    text-align: right;
+}
+
 main section p,
 main section table {
     max-width: 1000px;