Spirit Airlines ceased all operations on 2 May 2026, after its second Chapter 11 collapsed (NPR, 2 May 2026). The cheap domestic seats didn't disappear with it. They moved to Frontier, Allegiant, Breeze and Avelo, and anyone rebooking for the first time is about to find out that those four airlines do not measure a free bag the same way.

Two of them use a box that ex-Spirit flyers will recognise. Two of them are smaller.

What actually changed

Spirit stopped flying on 2 May 2026 and its routes were not transferred as a block to any single carrier. Ex-Spirit passengers are spread across four airlines with four separate baggage pages. The fare model is the same everywhere: a seat and one free underseat bag, everything else priced separately.

The free personal item, airline by airline

Every one of these four airlines gives every passenger one free personal item that must fit fully under the seat in front. Frontier and Allegiant publish an 18 x 14 x 8 inch limit. Breeze and Avelo publish smaller ones. All four count wheels, handles and straps in the measurement.

Frontier's personal item must be no larger than 14 inches high by 18 wide by 8 deep including handles, wheels and straps, and its paid carry-on tops out at 24 x 16 x 10 inches and 35 pounds. Allegiant publishes 8 x 14 x 18 inches for the personal item and 10 x 16 x 22 inches for the carry-on, and states plainly that airport bag fees apply to oversized personal items. Breeze allows 17 x 13 x 8 inches free on every fare, with carry-ons up to 22 x 14 x 9 inches and 35 pounds. Avelo's contract of carriage sets the free personal item at 17"L x 13"H x 9"W and the paid carry-on at 22 x 14 x 9 inches.

That two-inch spread matters. A bag sized for Frontier is over the limit on Breeze and Avelo in two dimensions.

None of them publish a flat carry-on price

All four price bags dynamically by route, date and when you buy, so there is no single number to quote. Frontier tells passengers to use its Bag Price Checker for accurate pricing rather than listing a fee. Allegiant routes the same question to its optional services table.

Buying at the gate is the worst tier everywhere. DeepArrival and The Points Guy put Frontier's gate carry-on between $99 and $115, against roughly $29 to $69 added at booking (checked September 2026). Allegiant says outright that prices at the airport are higher and pushes passengers to reserve bags in advance.

One more thing worth checking before you book Allegiant: its baggage page now carries a note about an Allegiant and Sun Country integration, and says trips will operate exactly as booked. Rules may shift as that progresses.

Picking your replacement

If the bag you bought for Spirit was built to 18 x 14 x 8, it still clears Frontier and Allegiant on paper and nothing else on this list. If you fly Breeze or Avelo, you need something closer to 17 x 13 x 8, and the extra inch of depth Avelo allows is the only concession you get.

Measure your own bag before you pack it. Then check the airline's website before you travel, because these numbers move.

Sources: NPR (2 May 2026); Frontier Airlines bag options page; Allegiant Air baggage page; Breeze Airways travel tips page; Avelo Airlines contract of carriage; DeepArrival and The Points Guy fee trackers. All airline pages checked September 2026.