Pay with Miles is at best 1 cent per mile, or in some cases less than 1 cent per mile. The minimum to pay the entire fare with miles is 25,000 miles, even if your fare is under $250. If the fare is over $100 though, you can get $100 off for 10,000 miles. Anything over $250 can be purchased in $50 increments for 5,000 miles each, or $100 increments for fares over $1000.