The developers behind Tumblr recommend using Google Analytics to check who views your Tumblr blog. Google Analytics is a free online tool to measure website traffic, which means you'll have access to a wide spectrum of data about your visitors, including what browser they used, how long they stayed on your blog and the most-viewed pages. Setting up Google Analytics with Tumblr is relatively easy. You can usually have the code installed on Tumblr in five minutes.
Log in or sign up for Google Analytics. Type "google.com/analytics" as the URL address to get there.
Click the "Add Website Profile" link.
Select the radio button for "Add a Profile for a new domain" and enter the domain information below. Click the "Finish" button to add your Tumblr blog.
Go to the "Paste this code on your site" section on the next page. Select and copy the text in the source code box. Press "Ctrl" + "C" on the keyboard to copy.
Sign in to your Tumblr account and click "Customize" from the dashboard menu.
Select the "Info" tab and paste the Google Analytics code into the "Description" field. If you already have a description there, paste it below. To paste text, press "Ctrl" + "V" on your keyboard.
Click the "Save" button. You will now be able to track and check who visits your Tumblr blog.
You can also see who your Tumblr followers are. To see them, log in to your account and click the "Follower" or "Followers" link from the on-site dashboard.