diff --git a/page/tsconfig.json b/page/tsconfig.json
index ff647ec..174cade 100644
--- a/page/tsconfig.json
+++ b/page/tsconfig.json
@@ -1,4 +1,4 @@
 {
   "extends": "astro/tsconfigs/strict",
-  "include": ["../src/scripts/**/*.ts"]
+  "include": ["../src/scripts/**/*.ts"],
 }
diff --git a/src/scripts/internal/api.ts b/src/scripts/internal/api.ts
index 2254eac..1f24767 100644
--- a/src/scripts/internal/api.ts
+++ b/src/scripts/internal/api.ts
@@ -152,3 +152,40 @@ export async function getRepoInfo(
   });
   return response;
 }
+
+/**
+ * Get the size of the repository in the specified branch.
+ * @param repo - The repository name in the format 'owner/repo'
+ * @param branch - The branch name
+ * @returns The size of the repository in KB
+ */
+export async function getRepoSize(
+  username: string | undefined,
+  reponame: string | undefined
+): Promise<number> {
+  const token = await getToken();
+  const headers = new Headers({
+    'User-Agent': 'Your-User-Agent', // Replace with your user agent
+    Accept: 'application/vnd.github.v3+json',
+    ...(token && { Authorization: `Bearer ${token}` }),
+  });
+
+  try {
+    const response = await fetch(
+      `https://api.github.com/repos/${username}/${reponame}`,
+      { headers }
+    );
+    if (!response.ok) {
+      throw new Error(
+        `Failed to fetch repo details: ${response.status} ${response.statusText}`
+      );
+    }
+
+    const data = await response.json();
+    const size = data.size;
+    return size;
+  } catch (error) {
+    console.error('Error fetching repository size for branch:', error);
+    return -1;
+  }
+}
diff --git a/src/scripts/internal/dom-manipulation.ts b/src/scripts/internal/dom-manipulation.ts
index 92f5170..f730424 100644
--- a/src/scripts/internal/dom-manipulation.ts
+++ b/src/scripts/internal/dom-manipulation.ts
@@ -3,7 +3,6 @@ import {
   createSizeSpan,
   createEmptySizeSpan,
   createTotalSizeElement,
-  formatBytes,
   getFileAnchors,
   getFirstTd,
   getNavButtons,
@@ -11,12 +10,14 @@ import {
   getRepoInfo,
   getSize,
   getSizeLabel,
+  getRepoSize,
   getTable,
   getThead,
   getTotalSizeButton,
   getTotalSizeSpan,
+  formatKilobytes,
 } from '.';
-import type { GRSUpdate, GitHubTree } from './types';
+import type { GRSUpdate, PathObject } from './types';
 
 /**
  * Insert the size label element into the table head.
@@ -100,7 +101,7 @@ function insertToFileExplorer(
  *
  * @param repoInfo - The repo info
  */
-function setTotalSize(repoInfo: GitHubTree) {
+async function setTotalSize(pathObject: PathObject) {
   const navButtons = getNavButtons();
   if (!navButtons) {
     return;
@@ -128,12 +129,9 @@ function setTotalSize(repoInfo: GitHubTree) {
     return;
   }
 
-  let totalSize = 0;
-  repoInfo.tree.forEach((item) => {
-    totalSize += item.size ?? 0;
-  });
+  const totalSize = await getRepoSize(pathObject.owner, pathObject.repo);
 
-  span.innerText = formatBytes(totalSize);
+  span.innerText = formatKilobytes(totalSize);
 
   navButtons.appendChild(totalSizeButton);
 }
@@ -213,7 +211,7 @@ export async function updateDOM() {
 
   insertSizeColumn();
 
-  setTotalSize(repoInfo);
+  setTotalSize(pathObject);
 
   updates.forEach(({ anchor, span, index }) => {
     // for some reason the rows have two td's with name of each file
diff --git a/src/scripts/internal/format.ts b/src/scripts/internal/format.ts
index 9683e26..771bbcc 100644
--- a/src/scripts/internal/format.ts
+++ b/src/scripts/internal/format.ts
@@ -23,3 +23,32 @@ export function formatBytes(bytes: number, decimals: number = 2): string {
   const i = Math.floor(Math.log(bytes) / Math.log(k));
   return parseFloat((bytes / Math.pow(k, i)).toFixed(dm)) + ' ' + sizes[i];
 }
+
+/**
+ * Formats a number in kilobytes to a string with a given amount of decimals.
+ *
+ * @param kilobytes - The number in kilobytes to format
+ * @param decimals - The number of decimals
+ * @returns The formatted string
+ * @example
+ * ```ts
+ * formatKilobytes(1024);
+ * // '1 KB'
+ * ```
+ * @example
+ * ```ts
+ * formatKilobytes(1024, 2);
+ * // '1.00 KB'
+ * ```
+ */
+export function formatKilobytes(
+  kilobytes: number,
+  decimals: number = 2
+): string {
+  if (kilobytes === 0) return '0 KB';
+  const k = 1000;
+  const dm = decimals < 0 ? 0 : decimals;
+  const sizes = ['KB', 'MB', 'GB', 'TB', 'PB', 'EB', 'ZB', 'YB'];
+  const i = Math.floor(Math.log(kilobytes) / Math.log(k));
+  return parseFloat((kilobytes / Math.pow(k, i)).toFixed(dm)) + ' ' + sizes[i];
+}
diff --git a/tsconfig.json b/tsconfig.json
index 36d909a..d2afef5 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -4,7 +4,7 @@
     "types": [
       "bun-types", // add Bun type definitions
       "./types.d.ts", // add your own type definitions
-      "@types/chrome"
+      "@types/chrome",
     ],
 
     // enable latest features
@@ -27,6 +27,6 @@
     // best practices
     "strict": true,
     "forceConsistentCasingInFileNames": true,
-    "skipLibCheck": true
-  }
+    "skipLibCheck": true,
+  },
 }