Tumblr supports static GIF images up to 10MB, and animated GIFs up to 1MB in size. You can use GIF images in posts and in your blog themes. You can resize your GIF images using any image editor, such as Adobe Photoshop, GIMP or even Microsoft Paint. If you use a professional editing application like Photoshop or GIMP, you have many more available options for resizing your images than with a program like Paint. For example, you can change the unit of measure from pixels to inches or millimeters.

Step 1

Open the GIF image in an image editor, such as GIMP, Photoshop or Microsoft Paint.

Step 2

Click the “Image” option in the top navigation menu.

Step 3

Click the “Image Size” option in Photoshop to open the Image Size dialog box. In GIMP, click “Scale Image” to open the resize tool. In Paint, click “Resize/Skew.”

Step 4

Type new values in the “Width and “Height” fields to specify the new image size. To change the unit of measure from pixels to inches or another value in GIMP and Photoshop, click the drop-down box, then select a different unit of measure. If you are using Paint, you can only resize the image to a percentage of the original. For example, type “90“ in the Width and Height fields to resize the image to 90 percent of its original size.

Step 5

Save the GIF image, and then upload the file to your Tumblr post or theme.