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Ontario to Colorado Flight Information

Flights Arrive in Colorado
Flights Depart from Ontario
Flight Price $117
Airlines Frontier, United Airlines, Delta, American Airlines, Alaska Airlines

Book cheap flights from Ontario to Colorado (round-trip)

Airports
Origin
Ontario
$117
only
$117
Destination
Denver
$117
only
$117
Tue, Apr 2
ONT
Ontario
DEN
Denver International
2h 13m
Tue, Apr 9
DEN
Denver International
ONT
Ontario
2h 30m
Trip: 8 days
7.1GoodShow reviews
Overall 7.1 Good
Based on 13 reviews
Overall
6.0
Boarding
6.4
Comfort
5.4
Crew
6.8
Entertainment
4.6
Food
4.7
ONT
DEN
Excellent 8.6

Pros: Early, friendly staff

Cons: No WiFi

CVG
LGA
Mediocre 3.5

Pros: Nothing

Cons: Flight was delayed by traffic control in NYC. Instead of just informing passengers why the flight was delayed, they just ignored the passengers and made people queue

BUF
DEN
Good 6.0

Cons: It’s was delayed 3 hours in buffalo .

LAS
DEN
Okay 5.0

Pros: These seats are beyond uncomfortable...The tray table serves no purpose but to hold a drink so it would be much more practical to have a cup holder.

ONT
DEN
Mediocre 2.0

Cons: 5 hour delay, horrible last minute communication. Second time in a row this has happened with Frontier. Will never fly them again at any price.

Wed, Mar 20
ONT
Ontario
DEN
Denver International
2h 13m
Tue, Mar 26
DEN
Denver International
ONT
Ontario
2h 30m
Trip: 7 days
7.5GoodShow reviews
Overall 7.5 Good
Based on 25 reviews
Overall
7.2
Boarding
7.4
Comfort
7.0
Crew
7.7
Entertainment
6.5
Food
6.5
EWR
BOS
Okay 5.6

Pros: plane flew on time

Cons: no longer allow roll on bags for free for economy. Didn't accept my KTN so couldn't use PreCheck. Couldn't get boarding pass on my phone before heading to airport. May be the last time I use United. Stone-age. Poor

SFO
IAD
Good 6.0

Pros: Was okay

Cons: Could have been in time waited seated in the plane for more than an hour due to technical problems , airline could have provided free refreshments at least as a consolation

ONT
DEN
Excellent 10.0

Pros: We were on time and the flights were excellent. Liked the way the pilot and the crew interacted

PSP
ORD
Good 7.6

Pros: Clean plane, nice staff

Cons: Small seats

IAH
AUS
Good 6.0

Pros: Captain kept us updated on everything going on, he made up time and got us to Austin pretty much on time. Staff was friendly. Huge plus was Houston’s terminal updates for United with iPads to order food - made it quick and easy to eat and run!

Cons: Gate was changed and Houston is a huge airport so lots of walking, flight was delayed, no snacks and only room temp water offered, no entertainment provided

Thu, Mar 28
ONT
Ontario
DEN
Denver International
6h 03m
Tue, Apr 2
DEN
Denver International
ONT
Ontario
2h 30m
Trip: 6 days
7.9GoodShow reviews
Overall 7.9 Good
Based on 22,976 reviews
Overall
8.1
Boarding
8.1
Comfort
7.8
Crew
8.5
Entertainment
7.7
Food
7.4
SYR
JFK
Good 7.3

Pros: Boarding was very smooth and the crew were helpful, efficient, and polite. There was a good assortment of entertainment.

Cons: I ordered the beef tenderloin, medium. It came out extremely rare and I had already eaten some by the time I realized; the entire plate was filled with blood. I ended up sick to my stomach for the remainder of the flight. Average height to tall individuals do not fit well laying down in the seats.

LAX
MEX
Mediocre 2.0

Pros: Nothing

Cons: Everything. Awful plane, seats and service

PDX
SLC
Good 6.6

Cons: Being on time

LGA
CLT
Excellent 10.0

Pros: Crew was great

Cons: I actually can not complain

JFK
BTV
Good 6.0

Cons: More room.

Mon, Apr 8
ONT
Ontario
DEN
Denver International
3h 59m
Tue, Apr 9
DEN
Denver International
ONT
Ontario
2h 30m
Trip: 2 days
7.2GoodShow reviews
Overall 7.2 Good
Based on 37,128 reviews
Overall
7.4
Boarding
7.5
Comfort
7.2
Crew
7.9
Entertainment
6.8
Food
6.7
MSP
CLT
Excellent 10.0

Pros: Landing and take off.

Cons: Nothing. Everything was great!

PHX
SBA
Excellent 9.2

Pros: Overall a very good flight

CLT
JFK
Excellent 10.0

Cons: Very good

MDT
CLT
Good 7.3

Cons: Stale pretzels

DFW
PHL
Good 6.3

Pros: Going on vacation

Cons: Tvs for all seats

Sat, Mar 16
ONT
Ontario
DEN
Denver International
6h 59m
Tue, Mar 19
DEN
Denver International
ONT
Ontario
2h 30m
Trip: 4 days
8.3ExcellentShow reviews
Overall 8.3 Excellent
Based on 25,717 reviews
Overall
8.6
Boarding
8.6
Comfort
8.3
Crew
8.9
Entertainment
7.9
Food
7.9
FLL
LAX
Good 7.3

Pros: Premium economy seats were great.

Cons: Bring your own ear buds or headphones.

SAN
SJC
Good 6.0

Pros: They were nice and calm workers.

Cons: I asked to check my bag while at the gate, and I was told yes just give me one second. They proceeded to call groups to enter the plane. I wasn’t helped. They forgot about me, then I went up 10 minutes before departure to board, and they told me I was late. It was a mess with overbooking too.

AUS
SEA
Excellent 8.0

Cons: There was no closed caption for the movies or at least myself and the stewardesses couldn’t figure it out!

PHX
PDX
Excellent 10.0

Pros: They gave me a premium class seat which was not expected or requested! Was super!

SFO
SEA
Excellent 8.0

Cons: Bigger leg room for tall peole 6 feet up...

Tue, Apr 9
ONT
Ontario
DEN
Denver International
2h 13m
Tue, Apr 16
DEN
Denver International
ONT
Ontario
2h 30m
Trip: 8 days
7.1GoodShow reviews
Overall 7.1 Good
Based on 13 reviews
Overall
6.0
Boarding
6.4
Comfort
5.4
Crew
6.8
Entertainment
4.6
Food
4.7
MCO
ISP
Excellent 8.0

Pros: Crew was great,seats not so comfortable

Cons: Snacks,drink,larger tray table

TPA
ORD
Mediocre 2.0

Cons: Waited 1 hour and 20 minutes for luggage. No excuse. Left us alone for an hour and then sent someone who was embarrassed to face us.

ONT
DEN
Mediocre 2.0

Cons: Due to all the delays on my first flight I just decided To re-book a different flight back I will never fly with this company again terrible the only reason they get a star because I can’t give them nine terrible

ONT
DEN
Okay 5.0

Pros: Nothing

Cons: Late. Late.Late Staff seemed rude

PHL
TPA
Excellent 8.3

Pros: The cree is amazing, the seat is too small and uncomfortable. The seats are only good for real short trip.

Wed, May 8
ONT
Ontario
DEN
Denver International
2h 23m
Wed, May 15
DEN
Denver International
ONT
Ontario
2h 14m
Trip: 8 days
7.1GoodShow reviews
Overall 7.1 Good
Based on 13 reviews
Overall
6.0
Boarding
6.4
Comfort
5.4
Crew
6.8
Entertainment
4.6
Food
4.7
OMA
DEN
Good 7.0

Pros: Friendlycree

Cons: Delayed 30 mins

CVG
LGA
Mediocre 3.5

Pros: Nothing

Cons: Flight was delayed by traffic control in NYC. Instead of just informing passengers why the flight was delayed, they just ignored the passengers and made people queue

MCO
DEN
Okay 4.4

Cons: Seats

DEN
STL
Okay 4.4

Cons: No WiFi - even for our HSE. Seats do not recline. Terrible turbulence.

DEN
SFO
Excellent 8.0

Pros: Friendliness of the SF counter agent.

Cons: Hidden charges! The quoted price did NOT include additional exhorbitant baggage charges, charges for in flight food and drinks, fixed seat backs. This was a classic case of bait and switch

Thu, Mar 21
ONT
Ontario
DEN
Denver International
2h 13m
Tue, Mar 26
DEN
Denver International
ONT
Ontario
2h 30m
Trip: 6 days
7.5GoodShow reviews
Overall 7.5 Good
Based on 25 reviews
Overall
7.2
Boarding
7.4
Comfort
7.0
Crew
7.7
Entertainment
6.5
Food
6.5
EWR
PTY
Mediocre 2.0

Pros: It was a stressful experience, arriving late for ur connection flight and find out u cant get to ur destination. I would say that they did compliment us with a very nice hotel so i apologize for the bad review i understand u cant do anything about the weather but was amazed with the hotel

ONT
DEN
Excellent 10.0

Cons: They crushed my luggage but replaced the carry on after.

IAH
MTY
Okay 4.0

Pros: Crew on flight was very nice. Plane has a lot of space for legs and comfortable seats. We got vouchers and a toothbrush with tooth paste (AT LEAST THAT) for our forced overnight stay.

Cons: Horrible experience. Plane had an engine issue and ended up being delayed for so many HOURS that we had to sleep in Houston. The organization was a big mess - so poor that we reached the hotel only at 130am while we had to wake up at 4ish am to be at the airport again by 5am.

EWR
BOS
Okay 5.6

Pros: plane flew on time

Cons: no longer allow roll on bags for free for economy. Didn't accept my KTN so couldn't use PreCheck. Couldn't get boarding pass on my phone before heading to airport. May be the last time I use United. Stone-age. Poor

PSP
ORD
Good 7.6

Pros: Clean plane, nice staff

Cons: Small seats

Sat, May 11
ONT
Ontario
DEN
Denver International
2h 23m
Wed, May 15
DEN
Denver International
ONT
Ontario
2h 14m
Trip: 5 days
7.1GoodShow reviews
Overall 7.1 Good
Based on 13 reviews
Overall
6.0
Boarding
6.4
Comfort
5.4
Crew
6.8
Entertainment
4.6
Food
4.7
PHL
SJU
Good 6.0

Pros: Yes

Cons: Food

MCO
ORD
Mediocre 2.0

Pros: Nothing, they cancelled my flight a day in advance.

Cons: They could have: 1) flown a plane in like other airlines 2) put me on another airline since they were unwilling to hold up their end of the agreement themselves.

DEN
IAH
Okay 4.0

Pros: Flight was delay 5 hrs..... with no one telling us anything.

RNO
DEN
Mediocre 2.0

Pros: Nothing.

Cons: Company lied about why flight was delayed in order to avoid costly reimbursement

ORD
RSW
Excellent 10.0

Pros: A great change since Frontier moved to Terminal 5 at O'Hare.

Mon, May 13
ONT
Ontario
DEN
Denver International
2h 23m
Wed, May 15
DEN
Denver International
ONT
Ontario
2h 14m
Trip: 3 days
7.1GoodShow reviews
Overall 7.1 Good
Based on 13 reviews
Overall
6.0
Boarding
6.4
Comfort
5.4
Crew
6.8
Entertainment
4.6
Food
4.7
DEN
PHX
Okay 5.5

Pros: Nothing out of the ordinary

Cons: Comfort/Seats

SAN
DEN
Okay 5.5

Pros: Loved the price

Cons: That you must pay for all drinks including water

MIA
LGA
Excellent 8.5

Pros: The crew, all female, were always polite and pleasant. The seats were sufficiently comfortable for the short trip to New York.

Cons: A wider aisle would have been significant. Consideration for long-legged travelers would always be appreciated!

LAS
RSW
Good 7.6

Pros: Crew was cool - seats were comfortable but

Cons: Not able to recline seats. Head rests did not have a cushion to pull around neck. AND - no charging stations for computers or phones - bad - looking elsewhere for my next flight. Come on, this is the charging age!

PWM
TPA
Excellent 9.0

Pros: Nonstop, pricing was great

Cons: Free stuff, seats and baggage. Maybe a real tray table instead of the shelf.

Sat, Mar 2
ONT
Ontario
DEN
Denver International
4h 13m
Tue, Mar 5
DEN
Denver International
ONT
Ontario
2h 30m
Trip: 4 days
7.2GoodShow reviews
Overall 7.2 Good
Based on 37,128 reviews
Overall
7.4
Boarding
7.5
Comfort
7.2
Crew
7.9
Entertainment
6.8
Food
6.7
DEN
DFW
Okay 5.0

Cons: Flight time was changed twice

PHX
SBA
Excellent 9.2

Pros: Overall a very good flight

BCN
MIA
Good 7.6

Cons: The on-boarding in Barcelona was a little odd. Instead of calling boarding by groups or zones it was a free for all. That could have been better organized

SBA
DFW
Good 6.0

Cons: Your seats are small and you never turn the fasten seatbelt light off

MSY
DFW
Good 7.6

Cons: Snack options aren’t good.

Mon, Mar 25
ONT
Ontario
DEN
Denver International
2h 09m
Thu, Apr 4
DEN
Denver International
ONT
Ontario
2h 30m
Trip: 11 days
7.5GoodShow reviews
Overall 7.5 Good
Based on 25 reviews
Overall
7.2
Boarding
7.4
Comfort
7.0
Crew
7.7
Entertainment
6.5
Food
6.5
OGG
SFO
Mediocre 3.6

Cons: Not having an eight hour delay due to poor scheduling of the airline.

LAX
SFO
Excellent 10.0

Pros: Yes, I got upgraded.

SFO
DEN
Mediocre 2.0

Pros: Nothing at all

Cons: It could have been on any airline but United

ONT
DEN
Excellent 10.0

Pros: Great staff.

Cons: A crying baby that say behind me.

IAD
SJD
Excellent 9.3

Pros: Non stop flight. The crew went out of their way to help us enjoy the flight. Food was available during most of the flight. The crew was friendly and enjoyed helping us get to our vacation

Cons: The entertainment system. I started watching a movie but couldn’t finish. Once the movie stoped I could not restart it.

Thu, Mar 28
ONT
Ontario
DEN
Denver International
6h 03m
Sun, Mar 31
DEN
Denver International
ONT
Ontario
2h 30m
Trip: 4 days
7.9GoodShow reviews
Overall 7.9 Good
Based on 22,976 reviews
Overall
8.1
Boarding
8.1
Comfort
7.8
Crew
8.5
Entertainment
7.7
Food
7.4
CLT
ATL
Excellent 10.0

Pros: Food good

ATL
HSV
Excellent 10.0

Cons: Quick 30 minute flight

JFK
BTV
Good 6.0

Cons: More room.

JFK
RDU
Okay 5.6

Pros: Boarding process was smooth.

Cons: In flight service was disappointing.

ABQ
ATL
Okay 5.6

Cons: I now know the downside of buying through Kayak, the ticket is non-upgradable even when seats became open and I offered to pay for the upgrade.

Tue, Mar 26
ONT
Ontario
DEN
Denver International
2h 13m
Thu, Apr 4
DEN
Denver International
ONT
Ontario
2h 30m
Trip: 10 days
7.5GoodShow reviews
Overall 7.5 Good
Based on 25 reviews
Overall
7.2
Boarding
7.4
Comfort
7.0
Crew
7.7
Entertainment
6.5
Food
6.5
ONT
DEN
Excellent 10.0

Cons: They crushed my luggage but replaced the carry on after.

SAN
SFO
Excellent 10.0

Pros: Lots of leg room!

SDF
IAD
Excellent 9.3

Pros: Crew amazing, smooth flight and on-time

Cons: Legroom and the fact that there is even s lower version of economy now! Yikes

ONT
DEN
Good 7.3

Pros: Upon arrival at my gate departing to Durham with a 2 year old handful. I was excited to hear the attendant call for travelers with small children to board first. The thought of boarding at the same time as everyone else was giving me anxiety.

Cons: Once I shuffled through tons disgruntled travelers because of my "child privilege" the attendant rolled her eyes and took a deep breath at the amount of time it took me to get to my ticket. Mind you, it makes sense I would have it somewhere convenient, but like I said single traveller, 2 year old handful. She scanned my ticket and flogged her hair in the air telling me take my stuff to the front of the plane. While the other attendant tagged all my items.

EWR
BQN
Okay 5.0

Pros: The seats on this airplane are very uncomfortable.

Cons: Flight left late, crew a bit unorganized seating passengers.

Sat, Apr 27
ONT
Ontario
DEN
Denver International
3h 59m
Sun, Apr 28
DEN
Denver International
ONT
Ontario
2h 30m
Trip: 2 days
7.2GoodShow reviews
Overall 7.2 Good
Based on 37,128 reviews
Overall
7.4
Boarding
7.5
Comfort
7.2
Crew
7.9
Entertainment
6.8
Food
6.7
SJU
DFW
Okay 4.0

Cons: Delayed was terrible. I arrived 7 hours later than expected.

TUS
ORD
Good 7.0

Pros: The flight was early.

Cons: More leg room needed.

LAS
DFW
Excellent 8.0

Pros: It’s economy so I didn’t expect much but there seemed to be more room than other flights from different carriers I’ve traveled with in the past.

Cons: Wasn’t impressed that I was charged for premium seating when my original flight was canceled three times in two days. I understand they can’t control the weather but my vacation was cut from seven days to 5 days.

LGA
DFW
Okay 4.3

Pros: service was consistent

Cons: Plane was unusually hot

JFK
CLT
Good 7.3

Pros: The crew was super nice and seat were comfy

Cons: I know that thing can happened but this flight was delayed an hour and half

Wed, May 8
ONT
Ontario
DEN
Denver International
2h 23m
Sat, May 18
DEN
Denver International
ONT
Ontario
2h 14m
Trip: 11 days
7.1GoodShow reviews
Overall 7.1 Good
Based on 13 reviews
Overall
6.0
Boarding
6.4
Comfort
5.4
Crew
6.8
Entertainment
4.6
Food
4.7
MCO
PVD
Excellent 8.6

Pros: I like the fact that the flight was on time, and boarding was quick..

ONT
DEN
Excellent 8.6

Pros: Early, friendly staff

Cons: No WiFi

ONT
DEN
Mediocre 2.0

Cons: 5 hour delay, horrible last minute communication. Second time in a row this has happened with Frontier. Will never fly them again at any price.

RNO
DEN
Mediocre 2.0

Pros: Nothing.

Cons: Company lied about why flight was delayed in order to avoid costly reimbursement

LAS
RSW
Good 7.6

Pros: Crew was cool - seats were comfortable but

Cons: Not able to recline seats. Head rests did not have a cushion to pull around neck. AND - no charging stations for computers or phones - bad - looking elsewhere for my next flight. Come on, this is the charging age!

Wed, Mar 27
ONT
Ontario
DEN
Denver International
2h 13m
Thu, Apr 4
DEN
Denver International
ONT
Ontario
2h 30m
Trip: 9 days
7.5GoodShow reviews
Overall 7.5 Good
Based on 25 reviews
Overall
7.2
Boarding
7.4
Comfort
7.0
Crew
7.7
Entertainment
6.5
Food
6.5
ONT
DEN
Excellent 10.0

Pros: Great staff.

Cons: A crying baby that say behind me.

SEA
DEN
Mediocre 2.6

Pros: The flight started with 7 min delay for one crew not showing up. Eventually we had to wait on the plane for one hour for the plane to fly

Cons: contacted customer service 3 times while the first 2 times over the phone and was promised to get a $100 travel voucher in 24-48 hours. Never got that. When called 3rd time I was asked to email their support which I did and one week have passed and nobody bothered to respond yet. Typical United!

DEN
SJD
Mediocre 3.0

Cons: Pilot didn’t show up, we waited 2.5 hours for him.

IAH
SLC
Good 6.0

Cons: The fight was fine. however on the flight to Houston they loaded one of my suitcases onto another flight. It arrived to late for me to get it before the ship left. Their customer service is horrible!!! They continually lied about where my luggage was. Never again!!!!!

EWR
MXP
Excellent 8.0

Pros: Crew was great

Cons: Not able to change our seat and I understood checked bag per person was included. The charged me 120 for two bagd

Fri, May 10
ONT
Ontario
DEN
Denver International
2h 23m
Wed, May 15
DEN
Denver International
ONT
Ontario
2h 14m
Trip: 6 days
7.1GoodShow reviews
Overall 7.1 Good
Based on 13 reviews
Overall
6.0
Boarding
6.4
Comfort
5.4
Crew
6.8
Entertainment
4.6
Food
4.7
ONT
DEN
Okay 5.0

Pros: I liked that there were no issues with my flight I was able to just board , get there and have no problems

Cons: I don’t like the fees for everything. It kinda just made me annoyed that there were fees attached to everything that doubled the cost of my flight.

RNO
DEN
Mediocre 2.0

Pros: Nothing.

Cons: Company lied about why flight was delayed in order to avoid costly reimbursement

ONT
DEN
Okay 5.0

Pros: Nothing

Cons: Late. Late.Late Staff seemed rude

OKC
MCO
Excellent 10.0

Pros: Friendly staff

MSY
PHL
Okay 5.3

Pros: Chairs don’t recline

Sat, Apr 20
ONT
Ontario
DEN
Denver International
6h 59m
Tue, Apr 23
DEN
Denver International
ONT
Ontario
2h 30m
Trip: 4 days
8.3ExcellentShow reviews
Overall 8.3 Excellent
Based on 25,717 reviews
Overall
8.6
Boarding
8.6
Comfort
8.3
Crew
8.9
Entertainment
7.9
Food
7.9
SFO
BNA
Good 6.0

Pros: One flight attendant was incredible! I dropped something and she helped me find it.

Cons: Once getting on the flight we sat for an hour, the seats were very Uncomfortable.

PDX
LAS
Excellent 9.5

Cons: Miss airline meals but realize this was a short flight. Everyone was great.

RDM
PDX
Mediocre 3.6

Pros: Onboard crew were ok but the gate staff were a bit sassy and rude.

Cons: Customers service training for gate agents.

PDX
JFK
Good 7.5

Pros: Good boarding process. Comfortable and shirt flight. Friendly crew. Limited drink offerings but green beer or wine offered.

Cons: No bathroom on plane (not announced before hand). Limited luggage storage space.

LAX
BWI
Excellent 10.0

Pros: Yes

Cons: I have flown Alaskan Airline that had movie screens. That would have been super since my flight wad 4 and half hours long

Wed, Mar 13
ONT
Ontario
DEN
Denver International
6h 03m
Sat, Mar 16
DEN
Denver International
ONT
Ontario
2h 17m
Trip: 4 days
7.9GoodShow reviews
Overall 7.9 Good
Based on 22,976 reviews
Overall
8.1
Boarding
8.1
Comfort
7.8
Crew
8.5
Entertainment
7.7
Food
7.4
AUS
ATL
Excellent 10.0

Pros: Getting offered a stipend to change flights - getting my preferred rental car

Cons: A direct flight

DCA
LGA
Mediocre 2.0

Pros: It was quick

Cons: Horribly shaky. Thought I was going to throw up. The male flight attendant came off as rude. Just happy I got off the plane alive because it was rough

LGA
MSP
Excellent 10.0

Pros: The crew was nice

Cons: The food

ATL
CDG
Okay 5.3

Cons: Don't call it "food." the meals were terrible. Also stop creating so much single use plastic.

PVG
ATL
Okay 4.0

Pros: Food were bad. Out of air condition

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