The old fee was $50.
That's on top of the $25 to check a first bag and $35 for a second bag, which are not changing.
The higher fees for bags over 50 pounds began for tickets bought after Feb. 1.
U.S. Airways says it's raising the fees to the same levels charged by other airlines.
It also raised fees on bags between 71 and 100 pounds.
Most airlines charge higher fees for luggage over 50 pounds.
Spirit Airlines, a small carrier that focuses on vacation passengers, recently began charging extra for bags above 40 pounds.
