The cost to upgrade to First Class on American Airlines is highly "dynamic" and depends on when and how you do it. If you upgrade at the time of booking, you are essentially just paying the fare difference, which can be anywhere from $100 to $1,000+ depending on the route. However, the best deals are often found as "Load Factor" offers in the American Airlines app after you have already booked; these "Buy Up" offers can be as low as $50 to $150 for short domestic hops if seats are empty. If you use miles, a domestic upgrade typically costs 15,000 miles plus a $75 co-pay (waived for some status levels). For elite status members (Gold, Platinum, etc.), upgrades are theoretically "free" but are subject to a waitlist hierarchy. In 2026, American has increasingly moved toward "monetizing" their first-class cabin, meaning they would rather sell an upgrade for $99 in the app than give it away for free to a status member, so checking the app daily is your best bet for a cheap seat in the front.