diff --git a/src/core/tileserver.js b/src/core/tileserver.js
index f8eeed5..5d92119 100644
--- a/src/core/tileserver.js
+++ b/src/core/tileserver.js
@@ -161,9 +161,9 @@ class CanvasUpdater {
     }
     for (let c = 0; c < this.maxTiledZoom; c += 1) {
       this.TileLoadingQueues.push([]);
-      const invZoom = this.maxTiledZoom - c - 1;
+      const invZoom = this.maxTiledZoom - c;
       // eslint-disable-next-line max-len
-      const timeout = TILE_ZOOM_LEVEL ** (2 * invZoom + 2) * (6 / TILE_ZOOM_LEVEL ** 2) * 1000;
+      const timeout = TILE_ZOOM_LEVEL ** (2 * invZoom) * (6 / TILE_ZOOM_LEVEL ** 2) * 1000;
       logger.info(
         `Tiling: Set interval for zoomlevel ${c} update to ${timeout / 1000}`,
       );
diff --git a/src/routes/tiles.js b/src/routes/tiles.js
index 8e1cf53..8a22cfa 100644
--- a/src/routes/tiles.js
+++ b/src/routes/tiles.js
@@ -6,44 +6,82 @@
 
 import fs from 'fs';
 import express from 'express';
+
+// eslint-disable-next-line import/no-unresolved
+import canvases from './canvases.json';
+import { getMaxTiledZoom } from '../core/utils';
 import { TILE_FOLDER } from '../core/config';
-import { HOUR } from '../core/constants';
 
 
 const router = express.Router();
 
+/*
+ * decide on cache length
+ */
+router.use('/:c([0-9]+)/:z([0-9]+)/:x([0-9]+)/:y([0-9]+).webp',
+  (req, res, next) => {
+    const { c: id } = req.params;
+    const canvas = canvases[id];
+    if (!canvas) {
+      next(new Error('Canvas not found.'));
+      return;
+    }
+    req.canvasId = id;
+
+    const maxTiledZoom = getMaxTiledZoom(canvas.size);
+    const { z: paramZ } = req.params;
+    const z = parseInt(paramZ, 10);
+    if (z < 0 || z >= maxTiledZoom) {
+      next(new Error('Invalid zoom level'));
+      return;
+    }
+    const invZoom = maxTiledZoom - z - 1;
+    const cacheTime = (15 + 180 * invZoom) * 60;
+    const pubCacheTime = Math.floor(cacheTime * 0.75);
+    res.set({
+      'Cache-Control': `public, s-maxage=${pubCacheTime}, max-age=${cacheTime}`,
+    });
+    next();
+  },
+);
+
 /*
  * get other tiles from directory
  */
-router.use('/', express.static(TILE_FOLDER, {
-  maxAge: 2 * HOUR,
-}));
+router.use(express.static(TILE_FOLDER));
 
 
 /*
  * catch File Not Found: Send empty tile
  */
-router.use('/:c([0-9]+)/:z([0-9]+)/:x([0-9]+)/:y([0-9]+).webp',
-  async (req, res) => {
-    const { c: paramC } = req.params;
-    const c = parseInt(paramC, 10);
-
-    const filename = `${TILE_FOLDER}/${c}/emptytile.webp`;
-    if (!fs.existsSync(filename)) {
-      res.set({
-        'Cache-Control': `public, s-maxage=${24 * 3600}, max-age=${24 * 3600}`,
-      });
-      res.status(404).end();
-      return;
-    }
+router.use(async (req, res) => {
+  const { canvasId } = req;
 
+  const filename = `${TILE_FOLDER}/${canvasId}/emptytile.webp`;
+  if (!fs.existsSync(filename)) {
     res.set({
-      'Cache-Control': `public, s-maxage=${2 * 3600}, max-age=${1 * 3600}`,
-      'Content-Type': 'image/webp',
+      'Cache-Control': `public, s-maxage=${24 * 3600}, max-age=${24 * 3600}`,
     });
-    res.status(200);
-    res.sendFile(filename);
+    res.status(404).end();
+    return;
+  }
+
+  res.set({
+    'Cache-Control': `public, s-maxage=${2 * 3600}, max-age=${1 * 3600}`,
+    'Content-Type': 'image/webp',
   });
+  res.status(200);
+  res.sendFile(filename);
+},
+);
+
+/*
+ * error handler
+ */
+// eslint-disable-next-line no-unused-vars
+router.use((err, req, res, next) => {
+  res.status(400).end();
+});
 
 
 export default router;