Flying while fat comes with a research project attached: every airline has a different rule for what happens if you don’t fit into a standard economy seat, and almost none of them make that rule easy to find before you’ve already paid for a ticket. This guide pulls together the actual policies, verified against each airline’s own documentation, plus the one binding legal precedent that exists anywhere in the world for a second seat at no extra cost.
This is a service piece, not a verdict on any airline’s decency. The point is to know what you’re walking into before you’re standing at a gate.
The basics: armrest, seatbelt, and who decides
Every policy in this article comes down to the same two tests, phrased slightly differently by each airline:
- The armrest test. If the armrest between two seats cannot be lowered because your body is in the way, or if your body extends past it into the neighboring seat, most airlines classify that as needing a second seat.
- The seatbelt test. Standard economy seatbelts run about 40 to 44 inches (102–112 cm) fully extended, depending on aircraft and airline. If that doesn’t close, you need an extension. Every airline operating in the US, UK and EU is legally required to carry seatbelt extenders on board and provide them free of charge — this is a safety requirement, not a courtesy, and asking for one is not optional information you owe anyone.
Who makes the call, and when, is where airlines diverge sharply.
Airline by airline
Southwest Airlines (US)
Southwest has run some version of a “Customer of Size” accommodation for more than 30 years, and it went through a very public back-and-forth in 2026. On 27 January 2026, Southwest tightened the policy to require pre-purchasing a second seat as part of its move to assigned seating. After weeks of passenger complaints and public criticism, the airline reversed course by late May 2026.
The current policy, confirmed directly on Southwest’s help center as of this writing:
- The armrest is the official boundary between seats.
- Booking two seats in advance is “strongly recommended” to guarantee adjacent seating, and that second seat is refundable after travel if the flight departed with at least one open seat.
- If you didn’t book ahead and it turns out you need the space, Southwest will give you a complimentary second seat at the gate — but only if adjacent seats are actually available. If the flight is full, you get rebooked, not squeezed in.
- One seatbelt extension per passenger, provided by Southwest, not usable in an exit row.
Southwest remains the only US major with a no-cost path built into the everyday policy, not just an emergency workaround.
American Airlines (US)
American has no free accommodation. If you need more space, you buy a second seat at 100% of the adult fare (plus taxes, minus passenger facility charges), booked in the same reservation as “EXST.” There’s no cap on how many extra seats you can buy. If you show up without having booked ahead, a gate agent will try to find two adjacent seats — and if that means a higher fare class, you pay the difference. (Source: American’s internal Extra Seat Procedures documentation, updated November 2025.)
Delta Air Lines (US)
Delta’s language is softer but the mechanics are similar: if you’ll encroach into the next seat or can’t lower the armrest, you’re “encouraged” to buy an extra seat in advance at the same fare, or upgrade to Premium Select, First, or Delta One. If you don’t, and the flight is full, you get rebooked. Delta does not refund extra-seat purchases on nonrefundable fares — a real difference from Southwest’s refund policy.
United Airlines (US)
United requires passengers who can’t fit in one seat, buckle the seatbelt (including with a 25-inch/64 cm extender), or lower the armrest to either pay for an extra seat or be rebooked. United first tries to reseat you next to an empty seat elsewhere on the plane at no charge before asking you to pay — the free option exists, but only when the flight has spare capacity.
British Airways (UK)
BA requires a second seat when a passenger can’t lower the armrest or encroaches into the neighboring seat; this must be booked at least 48 hours ahead through the airline or a travel agent, not online, and is charged at the standard or lowest applicable fare. Seatbelt extenders are carried on every aircraft and provided free on request. We could not verify specific weight or width thresholds sometimes quoted for BA (such as a fixed kilogram or centimeter cutoff) against BA’s own published policy, so we’re not repeating those numbers here — the airline’s stated criteria are the armrest and seatbelt fit, not a published measurement.
Ryanair (UK/EU budget)
Ryanair sells a second seat as a general “comfort” option, not a size-specific accommodation: you book two full-fare tickets, with the second passenger entered as “EXTRA COMFORT SEAT.” There’s no separate size policy, no reduced fare for the second seat, and no baggage allowance attached to it. Functionally this is the least accommodating option on this list — full price, no size-based framing, no free path.
Lufthansa, Eurowings, Condor (Germany)
None of the three has a formal published size policy. In practice, check-in staff try to find an empty neighboring seat on a case-by-case basis, and none of the three charges extra for it when they can. That’s more flexible day-to-day than the US majors, but it also means there’s nothing to point to in writing if a specific flight or a specific agent doesn’t accommodate you — no policy means no guarantee, in either direction.
The one legal right that actually exists: Canada
In January 2008, the Canadian Transportation Agency ruled that Air Canada, Air Canada Jazz and WestJet must offer “one person, one fare” on domestic flights to passengers who are, in the Agency’s language, “functionally disabled by obesity” and need a second seat, as well as to passengers with disabilities travelling with a required attendant. The airlines appealed; the Supreme Court of Canada declined to hear the case, so the ruling stands as binding precedent in Canada.
Two limits matter: it applies to domestic Canadian flights only, and it requires documentation of a disability-level need, not simply “I’d be more comfortable.” It has never been adopted in the US, the UK, or the EU. There is no equivalent minimum seat width or second-seat right anywhere in EU or German air passenger law — this is a gap, not an oversight anyone is currently required to close.
Booking tips that follow directly from the policies above
- Book the second seat when you book the first one, wherever a second-seat option exists (Southwest, American, Delta, United, BA, Ryanair all support this at booking). Showing up and hoping costs you the airline’s discretion, not your right.
- Ask about refund policy before you pay. Southwest refunds; Delta does not on nonrefundable fares; check before assuming either way.
- A seatbelt extender is not a downgrade or a favor. It’s required safety equipment every airline listed here must carry and provide free. You don’t need to justify asking for one.
- If flying Lufthansa, Eurowings or Condor, call ahead rather than relying on the gate, since there’s no written policy to invoke if a specific flight is full.
- Know your route. If you’re flying domestically within Canada, the one-person-one-fare right may apply to you if you can document a qualifying disability — worth investigating before you fly, not after a bad experience.
What this guide doesn’t do
It doesn’t rank airlines by kindness, and it doesn’t tell you your body is the problem here — a 17-inch economy seat is a design decision by the airline, not a fact about you. What it does is give you the actual rules, checked against each airline’s own published documentation where one exists, so you can plan a trip instead of gambling on one.
Sources
- Southwest Airlines, “What is your policy for Customers of size?” — support.southwest.com (fetched live, 28 July 2026)
- American Airlines, “Extra Seat Procedures” — saleslink.aa.com (updated November 2025)
- Delta Air Lines, “Extra Seat – Personal Comfort” — pro.delta.com
- Ryanair, “Can I buy an extra seat for comfort?” — help.ryanair.com
- Canadian Transportation Agency ruling, January 2008, and the Supreme Court of Canada’s 2009 refusal to hear the airlines’ appeal
- United Airlines and British Airways policies confirmed via independent secondary reporting where primary airline pages were not directly fetchable; unverifiable numeric thresholds (see British Airways section) were deliberately omitted