If you're deciding between Frontier and Spirit for a specific trip, add up the fees before you book — the base fare almost never tells the truth on either airline. As a rule of thumb: Spirit tends to charge slightly more for carry-ons and its "Big Front Seat," while Frontier's bag fees swing wildly depending on how far ahead you pay and whether you buy a bundle. The cheapest way to fly either one is to pay for every bag online during booking, travel with only a personal item if you can, and skip the airport counter at all costs. Below is exactly how the numbers break down so you can pick the one that costs you less.
The core difference: it's all about when you pay
Both Frontier and Spirit are ultra-low-cost carriers (ULCCs). That means the ticket price covers your seat and a personal item that fits under the seat in front of you — nothing else. Everything else is à la carte: carry-on bags, checked bags, seat assignments, printing a boarding pass at the counter, even a soda on board.
The single biggest cost trap on both airlines is paying for bags at the airport instead of online. Adding a bag during booking might cost $40–$60. Waiting until you're at the gate can push that same bag past $90–$99. The airlines design it this way on purpose — the fee structure punishes procrastination.
The second trap is the free personal item. On both carriers it must fit within roughly 18 x 14 x 8 inches. If your "personal item" is really a small carry-on, gate agents will make you pay the walk-up carry-on fee, which is the most expensive bag fee of all. Measure your bag before you leave home.
Baggage fees compared
Fees change constantly and vary by route, date, and demand, so treat these as representative ranges rather than fixed prices. The pattern, though, holds year to year.
| Item | Frontier (typical) | Spirit (typical) |
|---|---|---|
| Personal item (under seat) | Free | Free |
| Carry-on bag (paid online) | $40–$60 | $45–$65 |
| Carry-on at the gate | $90–$99 | $99+ |
| First checked bag (online) | $35–$55 | $40–$60 |
| Second checked bag (online) | $45–$65 | $50–$70 |
| Overweight bag (50–70 lb) | $50–$75 | $50–$75 |
| Seat assignment (standard) | $5–$50+ | $5–$50+ |
| Premium seat (extra legroom / Big Front Seat) | $18–$80 | $25–$250 (Big Front Seat) |
A quirk worth knowing: on many routes a checked bag is actually cheaper than a carry-on on both airlines. If you're bringing anything bigger than a backpack, price the checked bag first — you might save $10–$20 and skip lugging it through security.
The bundles: where Frontier and Spirit differ most
This is the clearest point of separation between the two. Both sell bundles that combine bags, seat selection, and flexibility, but they package them differently.
Frontier
Frontier restructured its fare tiers into named bundles like Economy, Premium, and Business (branding shifts periodically). Higher tiers roll in a carry-on, a checked bag, seat selection, and waived change fees. Frontier also sells an annual membership program (the "GoWild!" pass for unlimited standby flying and discount memberships) that can pay off if you fly the airline often — but the memberships come with their own recurring costs and blackout-style restrictions, so read the fine print.
Spirit
Spirit moved toward fare bundles as well, including options branded around more space and included bags. Its standout paid product is the Big Front Seat — a wide, first-class-style recliner with no middle seat, often for $25–$250 depending on the route. For a long, cramped ULCC flight, it's genuinely one of the better deals in the ultra-low-cost world if you value comfort.
Rule of thumb: if you need a carry-on plus a checked bag plus a seat assignment, price out the bundle against paying à la carte. On both airlines the bundle is frequently within a few dollars of buying everything separately — and occasionally cheaper.
Hidden costs people forget
- Airport boarding-pass printing. Both airlines can charge around $25 to print your boarding pass at the counter. Check in online and save it to your phone.
- Change and cancellation fees. Basic fares are the most restrictive. Both airlines have moved to waiving change fees on some fare types (following the industry after 2020), but ULCC basic fares often still carry fees, and you'll pay any fare difference on top.
- Seat selection creep. If you don't pay to pick a seat, you're assigned one for free at check-in — but families get split up this way. If you're traveling with kids, budget for seats. See our guide on flying with a baby or infant for how seating rules affect lap infants.
- Pet fees. Both airlines allow small pets in the cabin for a one-way fee (typically $99–$150). Read our flying with a pet guide before you book — carrier size limits are strict.
- Onboard purchases. No free snacks, no free water. A bottle of water can run $3–$4. Bring your own empty bottle and fill it past security.
- Third-party booking sites. Booking a ULCC through a discount travel site can lock you out of managing bags and seats directly, and add service fees. Book on the airline's own site.
Your rights when things go wrong
Low fares don't waive your federal protections. Under the 2024 DOT refund rule, if either airline cancels your flight or makes a significant change (generally a delay of 3+ hours domestic or 6+ hours international, a change in departure/arrival airport, added connections, or a downgrade) and you choose not to travel, you are owed an automatic cash refund to your original payment method — including all those bag and seat fees. You don't have to accept a voucher, and you shouldn't have to beg for it.
The US has no mandatory delay-compensation law like the EU's EU261. If your Frontier or Spirit flight is simply delayed and you still fly, the airline owes you only what its contract of carriage promises — which on ULCCs is very little. Don't expect hotel or meal vouchers for weather or air-traffic delays.
For lost or damaged checked bags on domestic flights, DOT sets airline liability at up to $3,800 per passenger. Keep receipts for essentials while your bag is delayed and file a claim promptly.
Overbooking still happens even on ULCCs. If you get involuntarily bumped, federal law requires cash compensation — up to 200% of your one-way fare (capped at $1,075) for a short domestic delay and 400% (capped at $2,150) for a longer one. Read the details in our guide to denied boarding compensation. If an airline stonewalls you on a refund or bag claim, you can file a DOT complaint — it's free and it works.
So which one is cheaper for you?
There's no universal winner — it depends on your route and what you carry. To decide:
- Search both for your exact dates and airports. ULCC pricing is hyper-local; Frontier might dominate one route while Spirit undercuts on another.
- Add your bags in the booking flow before comparing totals. The base fare is meaningless.
- Decide on comfort. Flying more than three hours? Spirit's Big Front Seat can be worth it. Frontier's stretch seating is cheaper but tighter.
- Factor in your home airport. Both airlines cancel and consolidate flights on thin routes; a slightly pricier ticket on the carrier with more daily frequencies can save you a stranded night.
If you're a light packer who can live with a personal item only, both airlines are genuinely cheap and roughly even. The moment you add bags and seats, run the full comparison — the "winner" flips constantly.
Frequently Asked Questions
Is a carry-on really more expensive than a checked bag on Frontier and Spirit?
Often, yes. On many routes both airlines price a carry-on higher than the first checked bag to discourage overhead-bin crowding. Always check both prices during booking — if they're close, checking your bag frees your hands and skips the security bin shuffle.
Can I avoid all the fees and just fly with the free personal item?
Yes, and it's the single biggest money-saver. As long as your bag fits under the seat (roughly 18 x 14 x 8 inches), you'll pay nothing beyond the fare. Pack light, wear your bulkiest layers, and you can fly a ULCC for close to the advertised price.
Do I get a refund if Frontier or Spirit cancels my flight?
Yes. Under the 2024 DOT rule, a cancellation or significant schedule change entitles you to an automatic cash refund of your fare and all fees if you choose not to travel — regardless of the fare type or how cheap the ticket was. Decline the voucher if you'd rather have your money back.
Is TSA PreCheck worth it if I'm flying budget airlines?
It can be, especially out of busy ULCC hubs where security lines run long. Since these airlines don't offer priority perks for free, PreCheck is one of the few ways to speed up your airport experience. See our comparison of TSA PreCheck, CLEAR, and Global Entry to decide which fits your travel pattern.