Is using a heating pad allowed on UA?
 

Also, any recommendations for a converter?

This is really a UA forum question.

I'm presuming you mean a 12v cigarette lighter style pad? I don't see why it wouldn't be. Tough part is finding a power outlet on most planes! P.S. planes have 110v power and the premium cabins of most international configs - but I have been seeing fewer and fewer empower ports on the domestic first seats.

I imagine something like this would work fine.

http://www.amazon.com/eForCity-Power...+12v+converter

What's the posted load of your heating pad?

I can't see the outlet having enough current to power a heating pad. It barely charges computers. The uncomfirmed output is 75W.