To set up a custom domain for your blog:

Choose a registrar, or use tools like Yahoo Domains or Domainr to find and buy a domain name that's available. (This usually costs about $10-$40 per year.) Note that Tumblr only allows your domain name to be 64 characters or less. Create a DNS record based on how many levels your custom domain contains. See the chart below.





Your registrar should have instructions on how to implement the proper CNAME or A-record.

Okay, now head over to Tumblr:

Click "Settings" under the account menu at the top of the dashboard, then choose the blog you’d like to update. Click the pencil to the right of the username section (Tumblr URL section for secondary blogs) and enable "Use a custom domain." Enter your domain (e.g., mywebsite.com) or subdomain (e.g., blog.mywebsite.com), then click “Test your domain.” Correct any problems if the test finds any, and click “Test your domain” until the test is successful. Hit “Save.”

Other things to note: