Lawyers could calculate an average value for a burn injury settlement. However, an average is just that. The value of your claim is going to depend on the unique details of your case.
Your claim could be worth a lot more than an average value. Your claim could also be worth less because of things like the effectiveness of treatment and your ability to continue working.
That said, claims for third or fourth-degree burns could be worth tens or hundreds of thousands of dollars or more. This is something that should be discussed with an experienced lawyer.