You can indeed use animated header images for your Tumblr blog theme. The Tumblr platform supports the use of animated GIFS for theme header images. However, Tumblr does place a few limitations on animated GIFS. For example, animated GIF files can be no larger than 1MB in size. If you upload an animated GIF image larger than 1MB, the first frame will display as a static graphic in your header. In addition, frames should not exceed 500 pixels in width.

Step 1

Log in to your Tumblr dashboard, then click the drop-down arrow next to your primary blog name. Click the name of the blog to edit.

Step 2

Click the “Customize” tab to open the blog in Edit mode. The Customize panel appears in the left sidebar.

Step 3

Click the “Upload” button in the Header Image section of the Customize panel. The file selector opens. Browse to and click the animated GIF to upload. Click “Open” to upload the file. The progress indicator displays while the file is uploaded. When the file is finished uploading, the Clear button appears next to the Upload button.

Step 4

Click “Save,” then click “Exit” to close the Customize panel and return to the dashboard.

Step 5

Click the URL for the blog in the right sidebar to view the animated GIF header on the blog.