There are a wide variety of themes available for the Tumblr blogging platform. A theme changes the look and feel of a Tumblr site, but does not modify individual blog posts. If you find a Tumblr blog that you like, you can use two methods to discover which theme it uses. The first method involves simply looking for an attribution or credit link in the footer, while the second requires you to view the source code of the site.
Access the Tumblr site that has the theme you like.
Scroll down to the footer area and look for a link to the theme. Many Tumblr blogs provide a reference to the theme in this area; however, some users remove this link, in which case proceed to the next step.
View the source code of the Tumblr page. If you're using Chrome or Firefox, right-click on the Tumblr page and select "View Page Source" from the context menu. On Internet Explorer, click the "View" menu, and then click "Source." If you're using Safari, select the "View" menu, and then choose "View Source."
Look for a link or mention of the theme near the top of the Tumblr source code. This is typically placed inside special brackets, such as " <!-- Theme: Example -->" (without the quotation marks).
Navigate to the Tumblr Themes Web page (link in Resources). Click the search icon, enter the name of the Tumblr theme that you have located, press "Enter," and then click on the desired theme from the results page.