Priority boarding is one of the most advertised perks on airline credit cards, but the reality varies a lot depending on which carrier you fly. A new breakdown of cobranded cards shows that 'priority' can mean anything from a genuine head start to a group that's barely ahead of the main cabin scramble — and that matters most when overhead bin space is tight.

The headline numbers: United cardholders get the best deal, boarding in Group 2 of 6 (effectively third overall). JetBlue's Premier and Business cards put you in Group 3 of 8. American Airlines AAdvantage cardholders board in Group 4 of 9 officially — but because the airline counts preboarding, family boarding and premium cabins separately, that's really the eighth of 13 groups. The premium AAdvantage Executive Mastercard buys you one extra group over other AA cards. Delta's SkyMiles Amex cards (Gold, Platinum and Reserve) land you in Zone 5 of 9, roughly ahead of general main cabin boarding but behind a long queue of elites and premium passengers.

Southwest cards guarantee Group 5 of 8, though you can move up if your fare or A-List status earns an earlier spot. Frontier's World Mastercard from Barclays gets you into Group 4 of 7 — the start of general boarding. Notably, the entry-level JetBlue Plus and JetBlue cards, along with American's no-fee MileUp card, don't include priority boarding at all, so check your card's benefits guide before assuming.

There's one quirk worth knowing before you swipe: for most airlines, you don't need to buy the ticket with the card. The perk is tied to your frequent flyer account, so as long as your loyalty number is on the reservation — including companions on the same booking — you board early even on an award ticket. Alaska and Hawaiian are the exceptions. There, you must actually pay for the flight with your Atmos Rewards Visa, and even then you only land in Group C, fourth of seven formal groups, behind elites and premium cabin passengers.

For travellers, the practical takeaway is to temper expectations. On United and JetBlue, the perk genuinely secures bin space. On American and Delta, you'll still be boarding behind a sizeable crowd, so an overhead spot isn't guaranteed on full flights. If boarding early is a priority for you, match the card to the airline you actually fly most — and remember that a few cards advertise the benefit while others in the same family quietly skip it.