Frontier vs United 2026: Carry-On Included on Most United Fares

Fees, policies, and figures in this comparison reflect what we verified as of Oct 2026 and can change afterward. Our live tools and the data behind them are re-verified more often than the written comparison.

Frontier Airlines and United Airlines share a hub at Denver International Airport. They compete on dozens of domestic routes, and the fare gap between them can be enormous: Frontier’s base fare can be a fraction of United’s cheapest option on the same city pair. That price difference is real, and it is why Frontier exists. But the price you see is not the price you pay, and the gap shrinks fast once you add the things United includes for free.

United is the better airline for the vast majority of travelers in 2026. It offers a free carry-on on every fare except domestic Basic Economy, free Starlink Wi-Fi for MileagePlus members on equipped aircraft, 373 destinations across six continents in 2025, and an on-time rate of 78.77 percent. Frontier counters with rock-bottom base fares, the highest loyalty program return rate among US carriers, and a new First Seats product launching in 2026. If you are flying short domestic routes with nothing but a backpack, Frontier can save you real money. For anything else, United delivers more for the total trip cost.

What We Looked For

• Total trip cost after bags, where Frontier’s base fare advantage often disappears
• On-time performance, a wide gap that matters for tight connections
• Standard seat pitch, where United publishes a figure per aircraft and Frontier publishes none
• Wi-Fi and entertainment, free Starlink versus no connectivity at all
• Network reach, roughly 120 destinations versus 373 across six continents
• Loyalty program value, Frontier Miles’ high return rate versus MileagePlus’ Star Alliance breadth
• Premium products, Frontier’s new first class versus United’s domestic first and Polaris

Bags and Fees Head-to-Head

This is where Frontier’s base fare math falls apart for most travelers. Every bag costs extra on Frontier. United includes a carry-on on every fare except domestic Basic Economy.

Carry-on. United allows one carry-on bag at 22x14x9 inches (56x35x23 cm) with no published weight limit on Economy, Economy Plus, and all premium fares. The bag is free. Frontier charges a dynamic fee for a carry-on at 24x16x10 inches (61x40.6x25.4 cm) with a 35 lb (16 kg) weight limit, cheapest when added at booking and most expensive at the gate. Frontier’s sizer box is taller and wider than United’s, but the weight cap and mandatory fee make it a worse deal.

On domestic Basic Economy, United also restricts you to a personal item only. But United cardholders and MileagePlus Premier members get the restriction waived, and international Basic Economy on United still includes a full carry-on.

Checked bags. United charges $45 prepaid online for the first checked bag at 50 lbs and 62 linear inches. Frontier prices checked bags dynamically and publishes no fixed fee, only a Bag Price Checker, for a bag capped at 40 lbs and 62 linear inches. Adding the bag at booking is cheaper than adding it later. That 40 lb limit is the lowest among major US carriers and will catch families and extended-trip travelers off guard. Frontier’s overweight fee for bags 51 to 100 lbs is $129. United’s first overweight tier, 51 to 70 lbs, is $100.

Personal item. United allows a personal item at 17x10x9 inches (43x25x22 cm). Frontier’s personal item sizer is 18x14x8 inches (45.7x35.6x20.3 cm). Both fit a standard backpack or laptop bag. Both are free on every fare.

Winner for carry-on value: United. Free on most fares, no published weight limit. Winner for checked bag cost: United. $45 prepaid at 50 lbs versus a dynamically priced Frontier bag capped at 40 lbs. Winner for carry-on sizer dimensions: Frontier. Taller and wider box fits more roller bags.

Winner: carry-on fee

United / free on most fares vs Frontier's paid carry-on

Winner: checked bag cost and weight

United / $45 at 50 lbs vs dynamic pricing at 40 lbs

Winner: carry-on sizer dimensions

Frontier / 24x16x10 vs 22x14x9

Seats and Comfort

Standard economy. United publishes pitch per aircraft: its 757-300 page lists 30 to 31 inches (76 to 78 cm) in Economy, and other types can differ. Frontier’s seating page says only that its Standard seats “come with standard legroom and space”, with no inch figure for its all-Airbus A320 family fleet. So there is no published gap to measure. Check the seat map for your flight if an inch matters to you.

Extra legroom. Both airlines sell extra-legroom seats. United’s Economy Plus runs 34 to 38 inches (86 to 96 cm) of pitch on the 757-300, available as a paid upgrade or complimentary for Premier status members. Frontier sells its Premium and UpFront Plus seats as extra legroom but gives no figure; its Premium seats are the only Frontier seats that recline. United’s is also available to frequent flyers for free.

Premium seats. Frontier is launching First Seats in 2026, with pre-reclined seats in the first two rows of the aircraft. The seats are wider and offer more space, but Frontier confirms they are pre-reclined and do not lie flat. United’s domestic first class offers full-recline seats with meal service, free drinks, and priority boarding. On international routes, United Polaris offers fully lie-flat suites with privacy dividers and new Polaris Studio ultra-premium suites rolling out on select 787s in 2026.

Entertainment and Wi-Fi. This is the widest gap in the comparison. United makes Starlink Wi-Fi free for all MileagePlus members, and membership itself is free. Not every plane has it yet: United is installing Starlink across the fleet and expects to finish before the end of 2027. Frontier offers no Wi-Fi, no seatback entertainment, and no power outlets. The airline has stated Wi-Fi is “coming” but has no confirmed timeline or provider.

Winner: standard seat pitch

Not published / United: 30-31 in on its 757-300; Frontier publishes no pitch

Winner: extra legroom recline

Frontier / Premium seats are the only ones that recline

Winner: premium seat product

United / full-recline first class and Polaris lie-flat

Winner: Wi-Fi

United / free Starlink vs no Wi-Fi at all

On-Time Performance and Cancellations

Frontier was the most-delayed major US airline in 2025, last of 10 on on-time arrivals (US DOT full-year 2025). United posted 78.77 percent on-time arrivals (Cirium full-year 2025). The gap is wide enough to matter on any tight connection.

Cancellation rates tell a similar story. Frontier cancelled 1.77 percent of flights in 2025. United cancelled 1.36 percent across its network (0.82 percent on mainline-only operations), per US DOT full-year 2025 data.

If your itinerary has a connection, the reliability gap matters even more. A delayed Frontier flight with no partner airline rebooking leaves you stranded until the next Frontier departure on that route. A delayed United flight can be rebooked across United’s 4,900 daily departures or onto Star Alliance partners.

Winner: on-time arrivals

United / 78.77% vs Frontier, the most-delayed major US carrier in 2025

Winner: cancellation rate

United / 1.36% vs 1.77% (US DOT 2025)

Winner: rebooking options

United / 4,900 daily flights + Star Alliance

Route Network

This is not a close comparison. United served 373 destinations across six continents in 2025 from seven US hubs: Newark, Chicago O’Hare, Denver, Houston, Los Angeles, San Francisco, and Washington Dulles. O’Hare alone has 672 daily departures connecting 197 destinations. United operates 46 transatlantic routes in summer 2026, including 14 European destinations that no other US carrier serves nonstop.

Frontier serves approximately 120 destinations across the US, Caribbean, Mexico, and Central America from its Denver hub and 12 focus cities including Orlando, Las Vegas, Atlanta, Cleveland, and Philadelphia. The airline announced 23 new routes for 2026, adding service from Detroit, Houston, Baltimore, Fort Lauderdale, Charlotte, and Dallas. But Frontier also reduced its fleet by 24 aircraft in early 2026 and deferred deliveries to 2031, signaling a shift toward route profitability over growth.

The Denver overlap is where both airlines compete most directly. Both operate heavy schedules from DEN, and on many DEN routes the fare comparison is apples-to-apples. On these routes, Frontier’s price advantage is often the most compelling because the flight time, airport, and schedule are identical.

Outside Denver, the comparison becomes less relevant. United serves markets Frontier does not touch: Asia, Europe, Africa, South America, Australia (via partners). If you need to fly internationally, United is the only option between these two.

Winner: destinations

United / 373 total vs about 120

Winner: international reach

United / six continents vs Mexico/Caribbean

Winner: Denver hub competition

Frontier / lower base fares on overlapping routes

Loyalty Programs

Frontier Miles earns 10 miles and 10 points per dollar spent on flights and ancillary purchases. U.S. News rates the program’s return at $13.92 per $100 spent, the highest among US airline loyalty programs by that measure. The program has five tiers (Basic through Elite Diamond), with Platinum members now eligible for complimentary first class upgrades. The catch: Frontier Miles has no airline partners. Your miles work only on Frontier. No alliance, no partner redemptions, no lounge access at any tier.

United MileagePlus is a Star Alliance program with earning and redemption across 25-plus partner airlines, including Lufthansa, Singapore Airlines, ANA, and Air Canada. As of April 2026, MileagePlus requires a minimum of four United or United Express segments per calendar year for Premier status qualification, making it more credit-card-centric than before. Premier status tiers unlock free upgrades, extra baggage, and United Club lounge access. Premier 1K members receive PlusPoints for long-haul Polaris upgrades.

For travelers who fly Frontier exclusively and frequently, Frontier Miles delivers strong per-dollar returns. For anyone who flies multiple airlines, travels internationally, or values lounge access and partner redemptions, MileagePlus is dramatically more useful.

Winner: per-dollar earning rate

Frontier / $13.92 per $100 spent

Winner: partner airline access

United / 25+ Star Alliance airlines

Winner: lounge access

United / United Club at Premier tiers

Winner: upgrade potential

United / complimentary upgrades + PlusPoints

Who Should Pick Frontier

• You are flying a short domestic route with only a personal item and the fare difference is $50 or more
• You live near Denver and Frontier offers the cheapest nonstop to your destination
• You fly Frontier often enough to reach Platinum status and want complimentary first class upgrades
• You are price-sensitive above all else and willing to forgo Wi-Fi, entertainment, and seat comfort
• You want Frontier’s Premium extra-legroom seating, which is also the only seat on the plane that reclines
• You are booking a leisure trip where arrival time flexibility is high and a delay is not a crisis

Who Should Pick United

• You need a carry-on bag included in your fare without purchasing a bundle or add-on
• You want free Wi-Fi on your flight, United’s Starlink is free for MileagePlus members on equipped aircraft
• You fly internationally or need connections beyond domestic US routes
• You value on-time reliability, United posted 78.77 percent on-time for full-year 2025 while Frontier ranked last of 10 (US DOT full-year 2025)
• You want a real first class or Polaris business class product with lie-flat seats
• You earn MileagePlus and want Star Alliance partner access, lounge benefits, and free upgrades
• You are checking a bag and want a 50 lb limit instead of Frontier’s industry-low 40 lbs
• You are connecting through a hub and need rebooking options if your first flight is delayed or cancelled

The Bottom Line

Frontier exists to win on the fare comparison page. When you sort by price, Frontier shows up first, and for travelers who can fly with a personal item only on a short domestic hop, that base fare savings is real. When Frontier’s ticket costs a fraction of United’s, that is a difference no amount of in-flight Wi-Fi makes up for.

But most travelers do not fly with just a personal item. Add a carry-on bag and Frontier’s dynamic fee eats into the gap. Add a checked bag and it narrows further, sometimes disappearing entirely. Factor in Frontier’s 40 lb checked bag weight limit (the lowest in the industry), its unpublished seat pitch, its last-place 2025 on-time rank (US DOT full-year 2025), and the total absence of Wi-Fi or entertainment, and the value proposition weakens on anything beyond a quick point-to-point flight.

United wins on the complete travel experience. Free carry-on, free Starlink Wi-Fi, a published 30 to 31 inches of Economy pitch on its 757-300, a global network with Star Alliance partners, and the operational reliability to get you where you are going on time nearly four out of five flights. The only question is whether the fare difference on your specific route is large enough to justify the tradeoffs. On a Denver-to-Vegas run with a backpack where Frontier’s fare is a fraction of United’s, Frontier makes sense. When the fares sit close and you need a bag, United is the obvious call.

For more comparisons, see Frontier vs Allegiant and United vs Spirit (kept for reference now that Spirit has shut down).