Allegiant, Spirit & Frontier Bag Fees Compared (2026)

US ultra-low-cost carriers (ULCCs) — Spirit, Frontier, and Allegiant — built their business model on advertising the lowest possible base fares, then charging for everything else. Carry-on bags are one of the biggest sources of ancillary revenue for all three. Understanding the fee structure before you book is the difference between a genuine deal and an expensive mistake.

Spirit Airlines Carry-On Fees

Spirit's pricing uses a sliding scale that punishes procrastination severely.

Personal item (free): Up to 18x14x8 inches. Must fit under the seat in front. No fee charged.

Carry-on bag (overhead bin):

• At booking online: approximately $45–$55 per flight
• After booking, online (up to 24 hours before departure): approximately $55–$65
• At airport check-in: approximately $65–$79
• At the gate: up to $99

Spirit enforces dimensions at the gate with a metal sizer. Bags that do not fit the personal item gauge are charged the gate rate — the highest possible fee — regardless of what you paid online.

Spirit's 2026 carry-on maximum is 22x18x10 inches. The personal item maximum is 18x14x8 inches. The gap between those two dimensions is where most of the fee disputes happen: a backpack that you believe is a personal item may be measured as a carry-on.

Frontier Airlines Carry-On Fees

Frontier operates on a bundle model where fees depend on which fare type you purchased.

Personal item (free): Up to 18x14x8 inches on all fares.

Carry-on bag (overhead bin):

• WORKS bundle or above: carry-on included in fare
• Basic fares (no bundle): carry-on fee starting around $39 at booking
• Pre-departure online add-on: approximately $49–$69
• Airport check-in: approximately $69–$89
• Gate: highest rate, typically $89+

Frontier's bundles — PERKS, WORKS — also include checked bags, seat selection, and refundability. If you need both a carry-on and a checked bag, the WORKS bundle often costs less than adding each item separately.

Frontier's carry-on maximum is 24x16x10 inches. The personal item maximum is 18x14x8 inches.

Allegiant Air Carry-On Fees

Allegiant is similar to Spirit in structure but with a slightly smaller personal item allowance.

Personal item (free): Up to 7x15x16 inches — notably smaller than Spirit or Frontier's personal item. This is approximately the size of a small purse or slim daypack.

Carry-on bag (overhead bin):

• At booking: approximately $35–$50 per flight
• Within 24 hours of departure: approximately $50–$65
• At airport check-in: approximately $55–$75
• At the gate: up to $75+

Allegiant flies primarily from smaller regional airports (not major hubs), which affects the competitive dynamic: there is often no legacy carrier alternative on the same route, making fee avoidance harder.

Personal Item Dimension Comparison

Airline	Personal Item Max	Carry-On Max
Spirit	18x14x8 in	22x18x10 in
Frontier	18x14x8 in	24x16x10 in
Allegiant	7x15x16 in	22x16x10 in

Allegiant's personal item restriction is meaningfully tighter than the other two. A standard small backpack that fits under Spirit's personal item definition may not qualify under Allegiant's — and will be charged as a carry-on at the gate.

When the Total Cost Exceeds Legacy Fares

Add a round-trip carry-on fee to a ULCC base fare:

• Spirit: base fare + $90–$110 round-trip carry-on fee
• Frontier: base fare + $78–$178 round-trip carry-on fee
• Allegiant: base fare + $70–$100 round-trip carry-on fee

On many routes, a Delta, United, or American basic economy ticket — which includes a free overhead carry-on on most domestic routes — prices at or below the ULCC total once bag fees are added. Use a flight search tool that shows total price with one carry-on included, not just the advertised base fare.

How to Minimize ULCC Bag Fees

Book the carry-on at the time of initial purchase. The gap between the booking rate and the gate rate is $40–$60 per flight. Buying at booking is the single highest-leverage action.

Use a co-branded credit card. Frontier's credit card includes a free carry-on per booking on Frontier flights. Spirit's card provides a free checked bag (not a carry-on) and other benefits. If you fly one ULCC regularly, the annual fee is typically recovered in one or two round trips.

Consider the personal item only. If your destination allows for minimal packing — a weekend trip, a business trip with no checked-bag needs — the under-seat personal item on Spirit (18x14x8 inches) holds more than people expect. A 20–25L packable daypack fits within those dimensions and serves as both a travel bag and an on-the-ground bag.

Compare total prices across carriers. A $129 Spirit fare plus $90 in bag fees ($219 total) versus a $189 Delta basic economy fare with carry-on included ($189 total) is not a close call — Delta is cheaper. Always compare total cost, not advertised fares.