Tongfamily.com

United has a very strange system for calculating mileage if you are a Mileage Plus member, basically, if you are a United 100K traveler, then any ticket you book from full-far economy to first class and even including discounted business is counted as 150% of your actual mileage flow for the purposes of getting to 100K miles, but the actual miles you earn are tieed from 150% for First (Fare classes F,A and P), 125% for full fare business (C and D). So your redemption and qualification can vary quite a bit.