Which has the bigger carry-on allowance, Allegiant or United?

Allegiant: 22 × 16 × 10 in (56 × 41 × 25 cm). United: 22 × 14 × 9 in (56 × 36 × 23 cm). Allegiant allows the larger bag.

Which is more reliable, Allegiant or United?

In 2025 Allegiant arrived on time 74.5% of the time (0.5% cancelled) and United 77.7% (0.8% cancelled), according to U.S. DOT data.

Which cancels fewer flights, Allegiant or United?

In 2025 Allegiant cancelled 0.5% of its flights and United 0.8%, so Allegiant had the edge (U.S. DOT data).

Are Allegiant and United partners?

They aren't in the same alliance (Allegiant: none; United: Star Alliance), so miles and status generally don't transfer between them.

G4 vs UA · 2026 comparison

Allegiant vs United

Q: Do Allegiant and United include a carry-on on basic economy?

Allegiant: Fares include only a personal item. A carry-on is a paid add-on, cheapest at booking. United: Basic Economy includes only a personal item on most U.S. and short-haul flights. A full-size carry-on is allowed on transatlantic, transpacific and South America routes, and for MileagePlus Premier members and eligible United cardmembers.

Allegiant wins on a bigger carry-on, a bigger personal item, cheaper checked bags and fewer cancellations; United wins on a carry-on on its cheapest fare and a better on-time record. Here's how they compare on bags, fees, comfort, reliability and loyalty.

Verified Oct 17, 2026By Steven MoHow we check Report a correction

Allegiant

Wins 4 categories

A bigger carry-on
A bigger personal item
Cheaper checked bags
Fewer cancellations

United

Wins 2 categories

A carry-on on its cheapest fare
A better on-time record

Quick verdict

Allegiant wins on a bigger carry-on, a bigger personal item, cheaper checked bags and fewer cancellations; United wins on a carry-on on its cheapest fare and a better on-time record. Check the cheapest fare's bag rules before you compare prices.

Carry-on size: Allegiant: 22 × 16 × 10 in · United: 22 × 14 × 9 in
Carry-on on the cheapest fare: Allegiant: Costs extra on basic fares · United: Not on some basic fares
First checked bag (regular economy): Allegiant: $20–$50 · United: $45
On-time arrivals (2025): Allegiant: 74.5% · United: 77.7%

Side by side

	Allegiant	United
Bags
Carry-on size	22 × 16 × 10 in	22 × 14 × 9 in
Carry-on on the cheapest fare	Costs extra on basic fares	Not on some basic fares
Carry-on weight limit	None published	None published
Personal item	7 × 15 × 16 in	17 × 10 × 9 in
First checked bag (regular economy)	$20–$50	$45
Reliability
On-time arrivals (2025)	74.5%	77.7%
Flights cancelled (2025)	0.5%	0.8%
Network
Alliance	None	Star Alliance
Loyalty program	Allways Rewards	MileagePlus
Main hubs	LAS, SFB, PIE, AZA	ORD, DEN, IAH, EWR, SFO

Highlighted values are better for travelers. Fees are for U.S. domestic economy flights; on-time data is 2025 U.S. DOT figures for each airline's own flights.

Bags and fees

Allegiant allows a carry-on up to 22 × 16 × 10 in (56 × 41 × 25 cm), and United up to 22 × 14 × 9 in (56 × 36 × 23 cm), so Allegiant's is roomier.

Allegiant charges for it on its cheapest fare, while United's Basic Economy can be personal-item only.

Neither publishes a carry-on weight limit.

Personal items: 7 × 15 × 16 in (18 × 38 × 41 cm) on Allegiant, and 17 × 10 × 9 in (43 × 25 × 23 cm) on United.

A first checked bag on Allegiant costs $20–$50 on all Allegiant flights, and a first checked bag on United costs $45 on U.S., Canada, Mexico, Central America and Caribbean flights.

Basic economy

Allegiant (Base fare): Fares include only a personal item. A carry-on is a paid add-on, cheapest at booking.

United (Basic Economy): Basic Economy includes only a personal item on most U.S. and short-haul flights. A full-size carry-on is allowed on transatlantic, transpacific and South America routes, and for MileagePlus Premier members and eligible United cardmembers.

On-time performance

In 2025, Allegiant landed 74.5% of its flights on time and cancelled 0.5%; United landed 77.7% on time and cancelled 0.8%. That makes United the more punctual of the two. The figures come from the U.S. DOT and count each airline's own flights, not regional partners.

Loyalty and where they fly

Allegiant is not in an alliance and United is in Star Alliance.

Loyalty programs: Allways Rewards (Allegiant) and MileagePlus (United).

Allegiant's main hubs are Las Vegas (LAS), Orlando Sanford (SFB), St. Petersburg–Clearwater (PIE), Phoenix–Mesa (AZA). United's are Chicago (ORD), Denver (DEN), Houston (IAH), Newark (EWR), San Francisco (SFO). The best choice often comes down to which airline flies nonstop from your airport.

Which should you book?

Choose Allegiant if you want…

a bigger carry-on
a bigger personal item
cheaper checked bags
fewer cancellations
nonstops from LAS, SFB, PIE

Choose United if you want…

a carry-on on its cheapest fare
a better on-time record
to earn and use Star Alliance miles and status
nonstops from ORD, DEN, IAH

On a route both fly, the cheaper ticket isn't always the cheaper trip: add the bags you'll actually bring, and check the fare rules before you book.