Since Tumblr doesn’t offer a way to export all the content at once, people have been developing online app that will will dump all your blog post into one XML file (using Tumblr API) which you can use to re-import into WordPress.
Here’s how to import your XML data file into wordpress
- Log into that blog as an administrator.
- Go to Manage: Import in the blog’s admin panels.
- Choose “WordPress” from the list.
- Upload this file using the form provided on that page.
- You will first be asked to map the authors in this export file to users on the blog. For each author, you may choose to map to an existing user on the blog or to create a new user
- WordPress will then import each of the posts, comments, and categories contained in this file into your blog