In what way can you tell how bad a burn is?

If the burn is ...: Red, dry, and tender, it may be a superficial 1st-degree burn. If it's blistered and painful, it may be a 2nd-degree burn. If it's covered by tough, leathery burned tissue and doesn't hurt, it may be a 3rd-degree burn. It's sometimes hard to tell the depth of scald or contact burns early on. Those that heal up within 3 weeks are 2nd-degree; if it's still open after 3 weeks, probably 3rd.