diff --git a/src/components/Bars.tsx b/src/components/Bars.tsx
index 298b6ad..278be55 100644
--- a/src/components/Bars.tsx
+++ b/src/components/Bars.tsx
@@ -25,6 +25,23 @@ function formatDomainName(url: string): string {
   return withoutWww.charAt(0).toUpperCase() + withoutWww.slice(1);
 }
 
+/**
+ * Converts a banner photo URL to its thumbnail version
+ * Replaces the filename with -small variant (e.g., image.jpg -> image-small.jpg)
+ */
+function getThumbnailUrl(bannerPhoto: string | null): string {
+  if (!bannerPhoto) return "/blueprint.jpg";
+
+  // Check if URL contains a file extension
+  const match = bannerPhoto.match(/^(.+)(\.[^.]+)$/);
+  if (match) {
+    return `${match[1]}-small${match[2]}`;
+  }
+
+  // Fallback to original if no extension found
+  return bannerPhoto;
+}
+
 interface GitCommit {
   sha: string;
   message: string;
@@ -393,9 +410,16 @@ export function LeftBar() {
                       <Typewriter class="flex flex-col" keepAlive={false}>
                         <div class="relative overflow-hidden">
                           <img
-                            src={post.banner_photo || "/blueprint.jpg"}
+                            src={getThumbnailUrl(post.banner_photo)}
                             alt="post-cover"
                             class="float-right mb-1 ml-2 h-12 w-16 rounded object-cover"
+                            onError={(e) => {
+                              // Fallback to full banner if thumbnail doesn't exist
+                              const img = e.currentTarget;
+                              if (img.src !== (post.banner_photo || "/blueprint.jpg")) {
+                                img.src = post.banner_photo || "/blueprint.jpg";
+                              }
+                            }}
                           />
                           <span class="inline wrap-break-word hyphens-auto">
                             {insertSoftHyphens(post.title.replace(/_/g, " "))}
diff --git a/src/lib/resize-utils.ts b/src/lib/resize-utils.ts
index 3cc47a2..83a7015 100644
--- a/src/lib/resize-utils.ts
+++ b/src/lib/resize-utils.ts
@@ -58,3 +58,83 @@ export function createIsMobile(
 ): Accessor<boolean> {
   return () => isMobile(windowWidth());
 }
+
+/**
+ * Resizes an image file to a maximum width/height while maintaining aspect ratio
+ * @param file Original image file
+ * @param maxWidth Maximum width in pixels
+ * @param maxHeight Maximum height in pixels
+ * @param quality JPEG quality (0-1), default 0.85
+ * @returns Resized image as Blob
+ */
+export async function resizeImage(
+  file: File | Blob,
+  maxWidth: number,
+  maxHeight: number,
+  quality: number = 0.85
+): Promise<Blob> {
+  return new Promise((resolve, reject) => {
+    const img = new Image();
+    const canvas = document.createElement("canvas");
+    const ctx = canvas.getContext("2d");
+
+    if (!ctx) {
+      reject(new Error("Failed to get canvas context"));
+      return;
+    }
+
+    img.onload = () => {
+      let { width, height } = img;
+
+      // Calculate new dimensions maintaining aspect ratio
+      if (width > maxWidth || height > maxHeight) {
+        const aspectRatio = width / height;
+
+        if (width > height) {
+          width = Math.min(width, maxWidth);
+          height = width / aspectRatio;
+        } else {
+          height = Math.min(height, maxHeight);
+          width = height * aspectRatio;
+        }
+      }
+
+      canvas.width = width;
+      canvas.height = height;
+
+      // Draw image on canvas with new dimensions
+      ctx.drawImage(img, 0, 0, width, height);
+
+      // Convert canvas to blob
+      canvas.toBlob(
+        (blob) => {
+          if (blob) {
+            resolve(blob);
+          } else {
+            reject(new Error("Failed to create blob from canvas"));
+          }
+        },
+        "image/jpeg",
+        quality
+      );
+    };
+
+    img.onerror = () => {
+      reject(new Error("Failed to load image"));
+    };
+
+    // Load image from file
+    const reader = new FileReader();
+    reader.onload = (e) => {
+      if (e.target?.result) {
+        img.src = e.target.result as string;
+      } else {
+        reject(new Error("Failed to read file"));
+      }
+    };
+    reader.onerror = () => {
+      reject(new Error("FileReader error"));
+    };
+    reader.readAsDataURL(file);
+  });
+}
diff --git a/src/lib/s3upload.ts b/src/lib/s3upload.ts
index a39b3a7..550946d 100644
--- a/src/lib/s3upload.ts
+++ b/src/lib/s3upload.ts
@@ -4,6 +4,7 @@
  */
 
 import { api } from "~/lib/api";
+import { resizeImage } from "~/lib/resize-utils";
 
 export default async function AddImageToS3(
   file: Blob | File,
@@ -26,7 +27,7 @@ export default async function AddImageToS3(
     const ext = /^.+\.([^.]+)$/.exec(filename);
     const contentType = ext ? `image/${ext[1]}` : "application/octet-stream";
 
-    // Upload file to S3 using pre-signed URL
+    // Upload original file to S3 using pre-signed URL
     const uploadResponse = await fetch(uploadURL, {
       method: "PUT",
       headers: {
@@ -39,6 +40,47 @@ export default async function AddImageToS3(
       throw new Error("Failed to upload file to S3");
     }
 
+    // For blog cover images, also create and upload a thumbnail
+    if (type === "blog") {
+      try {
+        // Create thumbnail (max 200x200px for sidebar display)
+        const thumbnail = await resizeImage(file, 200, 200, 0.8);
+
+        // Generate thumbnail filename: insert "-small" before extension
+        const thumbnailFilename = filename.replace(
+          /(\.[^.]+)$/,
+          "-small$1"
+        );
+
+        // Get pre-signed URL for thumbnail
+        const { uploadURL: thumbnailUploadURL } =
+          await api.misc.getPreSignedURL.mutate({
+            type,
+            title,
+            filename: thumbnailFilename
+          });
+
+        // Upload thumbnail to S3
+        const thumbnailUploadResponse = await fetch(thumbnailUploadURL, {
+          method: "PUT",
+          headers: {
+            "Content-Type": "image/jpeg" // Thumbnails are always JPEG
+          },
+          body: thumbnail
+        });
+
+        if (!thumbnailUploadResponse.ok) {
+          console.error("Failed to upload thumbnail to S3");
+          // Don't fail the entire upload if thumbnail fails
+        } else {
+          console.log("Thumbnail uploaded successfully");
+        }
+      } catch (thumbnailError) {
+        console.error("Thumbnail creation/upload failed:", thumbnailError);
+        // Don't fail the entire upload if thumbnail fails
+      }
+    }
+
     return key;
   } catch (e) {
     console.error("S3 upload error:", e);