How to upgrade your airplane seat: miles, bids, and standby

Every unsold first-class seat on every flight is a potential upgrade — but the path to it depends entirely on who you are to the airline. Complimentary upgrades work through a strict status ladder. Miles upgrades require advance planning. Fixed-price buy-ups are available to anyone willing to pay. And bid auctions — available on 50-plus international carriers but not at American, Delta, or United — let you name a price below full fare. Here is how each method works, what it costs, and how to pick the right one for your flight.

Complimentary upgrades go to elite status first — then to co-branded credit card holders

Every major US airline fills unsold premium seats by working down a priority list that starts at the highest status tier and ends with co-branded credit card holders. On Delta, all four Medallion tiers (Silver through Diamond) are eligible for unlimited complimentary upgrades to Delta First and Delta Comfort on domestic routes — Diamond and Platinum Medallion members additionally earn Upgrade Certificates as a Choice Benefit. Delta SkyMiles Reserve and Platinum American Express card holders receive complimentary upgrades as a card perk when seats are available after status holders clear. On United, Premier Platinum and above can request upgrades via PlusPoints on a waitlist; lower status tiers and Silver members have access to complimentary upgrade waitlists on select fare types.

• Priority order on every US carrier: highest status tier first, lower tiers next, co-branded card holders after
• Delta: all Medallion tiers (Silver, Gold, Platinum, Diamond) qualify; Diamond + Platinum also earn Upgrade Certificates
• United: PlusPoints upgrades reserved for Premier Platinum and above; waitlist closes at check-in cutoff
• American AAdvantage: Executive Platinum, Platinum Pro, Platinum, Gold — each tier gets a different upgrade window

How to use miles to upgrade your seat — costs, timing, and rules

Miles upgrades work best when booked early or monitored closely near departure. United lets you pay with miles for a Paid Cabin Upgrade from the moment you book all the way through check-in via My Trips — but you cannot use miles at an airport kiosk or gate, where only credit cards are accepted. Delta SkyMiles miles-plus-copay upgrades are requested on a waitlist and processed in status order. Domestic upgrade costs vary widely by route and availability. For a full look at how each airline structures fees, see airline fee comparisons.

• Delta SkyMiles domestic upgrade: approximately 7,500–25,000 miles plus a cash copay depending on route and cabin
• United MileagePlus domestic upgrade: approximately 7,500–20,000 miles; a MileagePlus Upgrade Award is put on a waitlist and miles are only deducted if the upgrade clears
• American AAdvantage: approximately 12,500–15,000 miles for a domestic first-class upgrade request; processed by status priority
• Miles are NOT accepted at airport kiosks or gates on United; request online or in-app before you arrive
• Award tickets may be ineligible for mileage upgrades depending on the program — check fare rules before booking

Delta, American, and United do not offer bid upgrades — they use fixed-price buy-ups instead

A common misconception is that all three major US carriers run Plusgrade-powered bid auctions. As of 2026, American, Delta, and United do not offer bid-to-upgrade programs; they instead offer fixed-price buy-ups where the airline names the price and you accept or decline. Delta's “Move Up” offer and American's and United's app-based upgrade prompts show a set dollar amount — you cannot submit a competing bid or name your own price. The only US carrier operating a true seat-upgrade auction is Hawaiian Airlines. You can review each carrier's check-in and upgrade policies on the airline guides hub.

• Delta Move Up: fixed-price offer to move to a higher cabin — not a variable bid
• American Airlines: app and email upgrade offers at a fixed price before departure
• United Paid Cabin Upgrades: money or miles at a set price visible in My Trips from booking through check-in
• Hawaiian Airlines:the sole US carrier using Plusgrade's auction system as of 2026
• Source: AFAR, March 4, 2026 — “those carriers don't offer bid-to-upgrade programs and rely instead on mileage upgrades, elite priority systems, and increasingly aggressive fixed-price buy-ups”

Which airlines let you bid for a seat upgrade — and what it costs

More than 50 airlines worldwide — primarily international carriers — run auction-style upgrade programs, many powered by Plusgrade, where economy passengers name a price for premium economy, business, or first class. Bidding windows typically open two to seven days before departure and close as few as five hours before the flight. Airlines set a floor price (the minimum bid), which is often at least a few hundred dollars for international routes; there is also a ceiling below the original premium-cabin fare. Winning bids automatically charge your card and include all premium-cabin perks: priority boarding, lounge access, checked bags, and premium meals.

• Bidding opens 2–7 days pre-departure; closes as few as 5 hours before departure
• Floor price is set by the airline — typically starting in the low hundreds of dollars for international routes
• Bid is per-person, per-leg — not for a full itinerary
• Check ExpertFlyer for unsold premium seats: more unsold seats generally favors a lower bid
• Winning bid does not change your original fare's miles-earning rate or refund terms
• Airlines with bid programs include: Aer Lingus, Air Canada, Air New Zealand, Avianca, Lufthansa, Virgin Atlantic, Hawaiian Airlines — but NOT American, Delta, or United

Gate and same-day upgrades: how to ask — and what to pay

If the premium cabin has unsold seats at departure, many airlines offer last-minute upgrades at the gate or kiosk for a flat fee. On United, the gate agent can sell an upgrade using a credit card if seats remain open. On domestic routes across major US carriers, same-day cabin upgrades typically run $99–$199 for short routes and $200–$400 for longer transcontinental segments. The best approach is to check in early online, look at the seat map to gauge available premium seats, and ask politely at the gate. Agents have more flexibility on quieter flights; showing up at a gate on an overbooked flight is not an effective strategy. Knowing your exact leave-by time matters here too — use the Leave-By Time calculator to build in enough time to approach the gate agent before the door closes.

• Check the seat map online after check-in opens (24 hours before): unsold first-class seats are a green light to ask
• United: credit cards only at kiosks and gates — miles cannot be used at the airport
• Domestic same-day upgrades: roughly $99–$199 for short routes, up to $400 on transcontinental segments
• Flights on small regional jets (Embraer E175s with ~12 first-class seats) go unsold most often — high-yield targets for gate upgrades
• Be polite and brief: “Is there a chance for an upgrade today?” works better than a long negotiation

Upgrade method comparison: miles, fixed buy-up, bid, and complimentary

Each upgrade method has a different cost structure, certainty level, and eligibility requirement. Complimentary upgrades are free but unpredictable; miles upgrades cost points but can be requested in advance; fixed-price buy-ups are certain but cost cash; and bid programs offer potential savings on international carriers at the price of uncertainty.

Basic economy is upgrade-ineligible — know which fares qualify before you book

Basic economy fares are blocked from all upgrade paths at American, Delta, and United — complimentary, miles, and paid. The ineligibility applies to bid programs on other carriers as well. You must hold at least a Main Cabin (United), Main (Delta Classic/Extra), or standard economy (American) fare to request any type of upgrade. Booking a basic economy ticket to save $20–$40 on a route you had planned to upgrade is almost always a false economy. Award tickets redeemed with miles may also be ineligible for further mileage upgrades depending on the booking class — check fare rules before assuming an upgrade is available.

• Basic economy: no complimentary upgrades, no miles upgrades, no paid upgrades, no bids
• United: “N” and “K” booking classes on award tickets are often ineligible for MileagePlus Upgrade Awards
• Delta: must purchase Classic or Extra experience fare to be upgrade-eligible
• American: AAdvantage award tickets in certain booking classes cannot be upgraded with miles
• Rule of thumb: if you plan to upgrade, never book the cheapest fare class available

Data verified June 29, 2026. Sources: Delta Medallion Upgrades, United MileagePlus Upgrades, AFAR — Bid Upgrade Airlines (Mar 2026).