What is the MIME type of .ico files?
The MIME type (media type) for Icon file files with the .ico extension is image/vnd.microsoft.icon. You may also see image/x-icon. Classic favicon format. Browsers also accept image/x-icon, which many servers send.
Content-Type header
Content-Type: image/vnd.microsoft.iconServer configuration
| Server | Configuration |
|---|---|
Nginx (mime.types or types {}) | image/vnd.microsoft.icon ico; |
Apache (.htaccess) | AddType image/vnd.microsoft.icon .ico |
IIS (web.config) | <mimeMap fileExtension=".ico" mimeType="image/vnd.microsoft.icon" /> |
| Node.js / Express | res.type('ico') or res.setHeader('Content-Type', 'image/vnd.microsoft.icon') |
| Amazon S3 | Set Content-Type: image/vnd.microsoft.icon on the object (metadata), or pass --content-type image/vnd.microsoft.icon to aws s3 cp |
Should .ico files be compressed?
Yes. Icon file is uncompressed data, so enabling gzip or Brotli for image/vnd.microsoft.icon typically saves 50–80 % of the transfer size. Make sure your server’s compression list includes this type — check with the website compression test.
Why the MIME type matters
Browsers decide what to do with a response — render, run, play or download — from the Content-Type header, not the file extension. With X-Content-Type-Options: nosniff, a wrong type causes stylesheets and scripts to be blocked outright. For uploads, never trust the type sent by the client; check the file’s content (its magic bytes) on the server.
Frequently asked questions
What is the MIME type for .ico?
image/vnd.microsoft.icon. Alternatives seen in the wild: image/x-icon.How do I set the Content-Type for .ico in Nginx?
image/vnd.microsoft.icon ico; is listed in the types block (usually in /etc/nginx/mime.types) and reload Nginx.