Find Cheap Flights from Ontario to Seattle/Tacoma Intl (ONT - SEA)

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Good to Know

Low Season:
January
Best time to beat the crowds
2%
expected price decrease
High Season:
November
Most popular time to fly
2%
expected price increase
Average Price:
$629
(avg. price over the last 2 weeks)
Good Deal:
$577
or less (round trip)

When to Book Flights from Ontario to Seattle/Tacoma Intl

Average price per month
Flight prices as travel date approaches
-1 day
-2 days

Top tips for Finding a Cheap Flight

The cheapest flight from Ontario to Seattle/Tacoma Intl was found 57 days before departure, on average.
Book at least 3 weeks before departure in order to get a below-average price.
High season is considered to be October, November and December. The cheapest month to fly is January.
Morning departure is around 15% more expensive than an evening flight, on average*.
*Average of the lowest prices shown in KAYAK’s search results for departures within the next 30 days

FAQs for Booking Ontario to Seattle/Tacoma Intl Flights

How long does a flight from Ontario to Seattle/Tacoma Intl take?
An average nonstop flight takes 2h 40m, covering a distance of 957 miles.
How many flights are there between Ontario and Seattle/Tacoma Intl?
There are 96 (nonstop) flights between Ontario and Seattle/Tacoma Intl per week, averaging 14 per day.
Which airlines provide the cheapest flights from Ontario to Seattle/Tacoma Intl?
In the past 3 days, the cheapest round-trip tickets were found on American Airlines ($114), Multiple Airlines ($126) and Delta ($134).
Do I need a passport to fly between Ontario and Seattle/Tacoma Intl?
No.
Which airlines fly most frequently between Ontario and Seattle/Tacoma Intl?
Alaska Airlines (8 times daily), American Airlines (4 times daily) are the most frequent flyers on this route.
What’s the cheapest day of the week to fly Ontario to Seattle/Tacoma Intl?
For Ontario to Seattle/Tacoma Intl, Friday is the cheapest day to fly on average and Tuesday is the most expensive. Flying from Seattle/Tacoma Intl back to Ontario, the best deals are generally found on Tuesday, with Friday being the most expensive.

Book cheap flights from Ontario to Seattle/Tacoma Intl (round-trip)

Airports
Origin
Ontario
$114
only
$114
Destination
Seattle
$114
only
$114
Fri, Mar 2
ONT
SEA
7h 39m
Tue, Mar 6
SEA
ONT
6h 39m
Trip: 5 days
7.2GoodShow reviews
Overall 7.2 Good
Based on 28211 reviews
Overall
7.4
Boarding
7.5
Comfort
7.1
Crew
7.8
Entertainment
6.7
Food
6.7
SJU
MIA
Excellent 9.3

New onboard entertainment

PHX
GEG
Good 7.3

The crew was friendly and informative. They were very helpful. The

The seats were uncomfortable. They were hard and so narrow I had to sit crooked in the seat to keep from getting banged into by the service carts and every person going by to the bathrooms. I'm not tiny, but I'm not huge either, it was just overcrowded. It was also very hot in the airplane the entire way from Phoenix to Spokane. My husband, who is always cold, was even hot.

ORD
CLT
Mediocre 3.0

Three hours delay. I paid for a upgrade to first class. But because of the flight change i didn't get to keep my upgrade and I had to beg for a refund. I have had two trips in the past 5 days and all flights have been anywhere from 1 to 3 hours late. Worst experience with AA I have had in a long time.

JAX
DFW
Excellent 8.6

Polite. Clean. Nice business class.

Would like more Western food.

DFW
FLL
Excellent 8.0

No issues at all

N/A

Fri, Mar 9
ONT
SEA
5h 06m
Tue, Mar 13
SEA
ONT
2h 27m
Trip: 4 days
Overall 0.0 Poor
Based on 0 reviews
Wed, Feb 28
ONT
SEA
6h 33m
Wed, Mar 14
SEA
ONT
5h 44m
Trip: 14 days
7.8GoodShow reviews
Overall 7.8 Good
Based on 16027 reviews
Overall
8.0
Boarding
8.1
Comfort
7.8
Crew
8.4
Entertainment
7.5
Food
7.4
BOS
JFK
Excellent 9.3

The volume controls on the tv we’re pretty poor. Was either too loud or too soft with only 5-6 volume settings.

GDL
ATL
Excellent 9.0

Staff was great!

No TV for movies.

BOS
ATL
Okay 4.0

Comfort Plus allowed us to board early, useful USB ports.

SJC
SLC
Excellent 8.8

Good clean aircraft. Fairly comfortable seats. Even had a power outlet in my row. Not too bad for an aircraft from the late 70s.

for some reason, i had to pay to gate check a bag. It didnt seem like anyone else did while boarding my flight.

DTW
MEX
Excellent 8.3

Even though I was disappointed by not being able to get the boarding passes from Delta for Aeromexico’s connecting flight to Bogota, I had an agent greet me after customs in Mexico to issue the boarding pass so I could use the transfer flight line. Excellent service throughout the entire trip.

Confusion over my boarding pass at the Delta terminal in Detroit.

Thu, Mar 15
ONT
SEA
2h 44m
Tue, Mar 27
SEA
ONT
2h 27m
Trip: 13 days
8.5ExcellentShow reviews
Overall 8.5 Excellent
Based on 86 reviews
Overall
8.6
Boarding
8.7
Comfort
8.4
Crew
8.9
Entertainment
7.9
Food
8.0
ONT
SEA
Good 7.0

My luggage was ripped open when I picked it up from the baggage claim in Ontario, CA.

ONT
SEA
Excellent 8.6

Need more fruit or veggie snack option No movie player option

ONT
SEA
Excellent 8.6

Sat in Premium. Early board because of wheel chair. Lots of room. Smooth flight. Arrived early in Seattle. Ta very nice. Took all way to car in parking lot. Cleanliness.

TA forgot one of my bags at security..but I didn't miss until almost to departure gate. Had to check my medicine bottle of cough syrup. What a pain. Put into separate basket. Open & swab. Weird. I'm 75 not a terrorist but I did have pneumonia recently & needed it do would not cough & choke on plane.

ONT
SEA
Excellent 8.3

Good selection of entertainment (movies).

ONT
SEA
Excellent 9.3

The food is really good and excellent vairity

Sometimes the staff is a littls bit impatient

Wed, Mar 7
ONT
SEA
5h 53m
Tue, Mar 13
SEA
ONT
4h 47m
Trip: 6 days
7.0GoodShow reviews
Overall 7.0 Good
Based on 54591 reviews
Overall
7.2
Boarding
7.4
Comfort
7.0
Crew
7.7
Entertainment
6.5
Food
6.4
IAD
GVA
Excellent 10.0

Best flight I have ever experienced!

Nothing

DEN
LAX
Okay 5.0

Great crew and process

For the fare, the leg room is not enough for average 6'0 person to be comfortable for longer than an hour.

IAH
HNL
Excellent 9.3

The flight crew was very welcoming and positive. They were attentive and ensures that every one had headsets, blanckets etc for the 8.5 hour flight.

Lacking food healthy food options. No salads or light bites available. The warm food that they did have was terrible and very salty. I wish their in-flight entertainment was not on our own devices because updates to the app are required which you wouldnt know unless you were on the plane and connected to their wifi.

SJO
IAH
Mediocre 3.3

The check-in staff were very friendly and helpful.

I already knew I was going to pay $200 to ship my boards back home (I wonder if golf clubs which are roughly the same size cost as much,) but when pre-purchasing through the app for an "oversized" bag you have to put a "one" in the checked bag and a "one" in the oversized bag even though they're the same bag, but then they charge you for two, and when you tell the check-in person that you only have one bag of course they can't issue a refund. No, they tell you that you get to call customer service when you return home.

LAX
LHR
Excellent 10.0

United Airlines team and the plaine were brilliant.

Thu, Mar 1
ONT
SEA
20h 50m
Tue, Mar 6
SEA
ONT
18h 09m
Trip: 6 days
5.7OkayShow reviews
Overall 5.7 Okay
Based on 33843 reviews
Overall
5.9
Boarding
6.4
Comfort
5.4
Crew
6.8
Entertainment
4.5
Food
4.7
IAD
SAT
Mediocre 3.6

The crew was helpful and apologetic.

They purposefully understaffed the check in counter, which you have to use. They charge for every little thing, even carry on bags and snacks. The seats might as well be lawn chairs. They are so close together everyone onboard will die from head injuries if there's an accident. I'll fly Southwest from now on.

BUF
MCO
Good 7.3

Flight was great. Checkin etc was great

ORD
RSW
Good 6.0

Crew was super nice

Delayed 3 hours, boarded and was told would be another 30minutes because of mechanical issues.

DCA
DEN
Excellent 8.0

Friendly staff

Didn't like I wasn't offered a cup of water and they nickel and dime you for EVERYTHING!

DEN
ORD
Excellent 9.6

They left me alone.

Fold down tables are tiny

Thu, Mar 1
ONT
SEA
6h 33m
Wed, Mar 14
SEA
ONT
5h 44m
Trip: 13 days
7.8GoodShow reviews
Overall 7.8 Good
Based on 16027 reviews
Overall
8.0
Boarding
8.1
Comfort
7.8
Crew
8.4
Entertainment
7.5
Food
7.4
BOS
ATL
Okay 4.0

Comfort Plus allowed us to board early, useful USB ports.

ATL
JNB
Okay 4.0

Aircraft seemed shabby despite refresh of Comfort Plus, food was really mediocre. Steer clear of the Asian Veg option.

SJC
SLC
Excellent 8.8

Good clean aircraft. Fairly comfortable seats. Even had a power outlet in my row. Not too bad for an aircraft from the late 70s.

for some reason, i had to pay to gate check a bag. It didnt seem like anyone else did while boarding my flight.

DTW
MEX
Excellent 8.3

Even though I was disappointed by not being able to get the boarding passes from Delta for Aeromexico’s connecting flight to Bogota, I had an agent greet me after customs in Mexico to issue the boarding pass so I could use the transfer flight line. Excellent service throughout the entire trip.

Confusion over my boarding pass at the Delta terminal in Detroit.

BOS
BNA
Excellent 8.0

Service vey Good. Nice choices. Comfort seating very nice

WiFi awful. Useless.

Wed, Mar 21
ONT
SEA
2h 44m
Tue, Mar 27
SEA
ONT
2h 27m
Trip: 7 days
8.5ExcellentShow reviews
Overall 8.5 Excellent
Based on 86 reviews
Overall
8.6
Boarding
8.7
Comfort
8.4
Crew
8.9
Entertainment
7.9
Food
8.0
ONT
SEA
Excellent 10.0

The trip was smooth and worry free

Everything was great. As a matter of fact, I shared in a couple of recent conversations how much I like Alaska.

ONT
SEA
Excellent 8.6

Need more fruit or veggie snack option No movie player option

ONT
SEA
Good 6.0

Nice clean planes

No entertainment monitors

ONT
SEA
Good 7.0

My luggage was ripped open when I picked it up from the baggage claim in Ontario, CA.

ONT
SEA
Excellent 9.3

The food is really good and excellent vairity

Sometimes the staff is a littls bit impatient

Thu, Mar 1
ONT
SEA
6h 33m
Sat, Mar 3
SEA
ONT
4h 27m
Trip: 3 days
Overall 0.0 Poor
Based on 0 reviews
Thu, Mar 8
ONT
SEA
5h 53m
Tue, Mar 13
SEA
ONT
5h 25m
Trip: 5 days
7.0GoodShow reviews
Overall 7.0 Good
Based on 54591 reviews
Overall
7.2
Boarding
7.4
Comfort
7.0
Crew
7.7
Entertainment
6.5
Food
6.4
GRR
IAH
Good 6.0

Pay for food, cold on plane entire time, everyone bundled up in blankets, jackets but staff friendly

DEN
IAH
Mediocre 2.0

Nothing

Never made it. Stuck in Denver.

IAH
SAN
Mediocre 2.6

The staff were fine, nothing really great, but nothing bad either.

So, we'll start with boarding. Why airlines can't figure out to board the plane from back to front is beyond me. No, let's load front to back so everyone has to uncomfortably shove past the people who have already taken their seats at the front of the plane. Then you get back there and all the overhead bins are full because everyone takes as many bags as possible onto the plane. Then you have to sacrifice the already tiny amount of foot room, "to put the bag fully underneath the seat in front of you." At this point you should be fine, except if you're over five and a half feet tall (I don't know if that's true I'm 6'2" and 275 lbs,) because then your knees are going to be buried so deep in the chair in front of you that the person up there doesn't even need a seat they can just sit on your knees. Luckily for you tall people, they put a nice metal rod just about knee level to really dig in and cause pain . . . Yay! Being a big guy, you try to be considerate and fold your arms in to give the person next to you as much space as possible, but don't expect that back as they'll spread out and become as wide as possible. Then to distract yourself from the discomfort, you try to use the free in flight entertainment via the United app, but "it's not available right now." In summation either be short and small or be rich and buy the seats with extra legroom when you fly United.

DFW
ORD
Excellent 10.0

I LIKE THE SERVICE ON BORD OF THE PLANE

NOTHING

IAH
HNL
Excellent 9.3

The flight crew was very welcoming and positive. They were attentive and ensures that every one had headsets, blanckets etc for the 8.5 hour flight.

Lacking food healthy food options. No salads or light bites available. The warm food that they did have was terrible and very salty. I wish their in-flight entertainment was not on our own devices because updates to the app are required which you wouldnt know unless you were on the plane and connected to their wifi.

Thu, Mar 22
ONT
SEA
2h 44m
Mon, Mar 26
SEA
ONT
2h 25m
Trip: 5 days
8.5ExcellentShow reviews
Overall 8.5 Excellent
Based on 86 reviews
Overall
8.6
Boarding
8.7
Comfort
8.4
Crew
8.9
Entertainment
7.9
Food
8.0
ONT
SEA
Excellent 9.3

The food is really good and excellent vairity

Sometimes the staff is a littls bit impatient

ONT
SEA
Good 6.0

Nice clean planes

No entertainment monitors

ONT
SEA
Excellent 8.6

Need more fruit or veggie snack option No movie player option

ONT
SEA
Excellent 8.6

Food I purchased was very good

Food was not priced well. NO WIFI??? WHAT?

ONT
SEA
Excellent 8.6

Sat in Premium. Early board because of wheel chair. Lots of room. Smooth flight. Arrived early in Seattle. Ta very nice. Took all way to car in parking lot. Cleanliness.

TA forgot one of my bags at security..but I didn't miss until almost to departure gate. Had to check my medicine bottle of cough syrup. What a pain. Put into separate basket. Open & swab. Weird. I'm 75 not a terrorist but I did have pneumonia recently & needed it do would not cough & choke on plane.

Wed, Mar 7
ONT
SEA
4h 45m
Sat, Mar 10
SEA
ONT
6h 15m
Trip: 4 days
Overall 0.0 Poor
Based on 0 reviews
Wed, Apr 18
ONT
SEA
5h 10m
Tue, Apr 24
SEA
ONT
4h 57m
Trip: 7 days
7.0GoodShow reviews
Overall 7.0 Good
Based on 54591 reviews
Overall
7.2
Boarding
7.4
Comfort
7.0
Crew
7.7
Entertainment
6.5
Food
6.4
DFW
ORD
Excellent 10.0

I LIKE THE SERVICE ON BORD OF THE PLANE

NOTHING

GRR
IAH
Good 6.0

Pay for food, cold on plane entire time, everyone bundled up in blankets, jackets but staff friendly

LGA
IAH
Good 6.3

I was told that I had to gate check my bags which had all of the necessities to travel with my child ( snacks, books, toys) due to it being a full flight. When I boarded, there were still several overhead storage bins completely empty. Very annoying. The crew could have physicallt assessed and checked before assuming due to flight capacity.

LAX
LHR
Excellent 10.0

United Airlines team and the plaine were brilliant.

DEN
LAX
Okay 5.0

Great crew and process

For the fare, the leg room is not enough for average 6'0 person to be comfortable for longer than an hour.

Wed, Mar 21
ONT
SEA
6h 12m
Tue, Mar 27
SEA
ONT
18h 09m
Trip: 7 days
5.7OkayShow reviews
Overall 5.7 Okay
Based on 33843 reviews
Overall
5.9
Boarding
6.4
Comfort
5.4
Crew
6.8
Entertainment
4.5
Food
4.7
TPA
LAS
Okay 4.3

Very reasonable price.

You literally have to pay for even the basic things, including for seats to recline. Cushion on seats thin and seats don't recline. 5hrs flight and No entertainment, no tv, no radio, no complimentary food...they offered a cup of water.

ORD
RSW
Good 6.0

Crew was super nice

Delayed 3 hours, boarded and was told would be another 30minutes because of mechanical issues.

MKE
TPA
Mediocre 2.0

the flights and attendents were good ,flight was delayed almost 2 hours on my return flight

didnt have to pay for luggage on first flight put under seat on return flight the girl at ticket counter was rude to me and charged me 45.00 for my bag i put under my seat and she was not a pleasant person to deal with, i wouldnt fly frontier again

PHL
DEN
Mediocre 2.0

This is actually almost a funny question because Frontier is the worst Airlines well actually that's not true spirit is the worst Airlines the seats are uncomfortable it takes about an hour and a half to just put your bags and baggage drop and then when you get on the plane They don't serve you anything they have no entertainment your crowded in can't move people are rude worst hairlines ever

Every single thing

DEN
ORD
Excellent 9.6

They left me alone.

Fold down tables are tiny

Sat, May 5
ONT
SEA
4h 45m
Wed, May 30
SEA
ONT
5h 45m
Trip: 26 days
Overall 0.0 Poor
Based on 0 reviews
Fri, Apr 20
ONT
SEA
5h 10m
Tue, Apr 24
SEA
ONT
4h 57m
Trip: 5 days
7.0GoodShow reviews
Overall 7.0 Good
Based on 54591 reviews
Overall
7.2
Boarding
7.4
Comfort
7.0
Crew
7.7
Entertainment
6.5
Food
6.4
LAX
LHR
Excellent 10.0

United Airlines team and the plaine were brilliant.

LGA
IAH
Good 6.3

I was told that I had to gate check my bags which had all of the necessities to travel with my child ( snacks, books, toys) due to it being a full flight. When I boarded, there were still several overhead storage bins completely empty. Very annoying. The crew could have physicallt assessed and checked before assuming due to flight capacity.

IAH
SAN
Mediocre 2.6

The staff were fine, nothing really great, but nothing bad either.

So, we'll start with boarding. Why airlines can't figure out to board the plane from back to front is beyond me. No, let's load front to back so everyone has to uncomfortably shove past the people who have already taken their seats at the front of the plane. Then you get back there and all the overhead bins are full because everyone takes as many bags as possible onto the plane. Then you have to sacrifice the already tiny amount of foot room, "to put the bag fully underneath the seat in front of you." At this point you should be fine, except if you're over five and a half feet tall (I don't know if that's true I'm 6'2" and 275 lbs,) because then your knees are going to be buried so deep in the chair in front of you that the person up there doesn't even need a seat they can just sit on your knees. Luckily for you tall people, they put a nice metal rod just about knee level to really dig in and cause pain . . . Yay! Being a big guy, you try to be considerate and fold your arms in to give the person next to you as much space as possible, but don't expect that back as they'll spread out and become as wide as possible. Then to distract yourself from the discomfort, you try to use the free in flight entertainment via the United app, but "it's not available right now." In summation either be short and small or be rich and buy the seats with extra legroom when you fly United.

DFW
ORD
Excellent 10.0

I LIKE THE SERVICE ON BORD OF THE PLANE

NOTHING

DEN
LAX
Okay 5.0

Great crew and process

For the fare, the leg room is not enough for average 6'0 person to be comfortable for longer than an hour.

Wed, Aug 1
ONT
SEA
4h 45m
Thu, Aug 9
SEA
ONT
4h 08m
Trip: 9 days
Overall 0.0 Poor
Based on 0 reviews
Fri, Mar 2
ONT
SEA
2h 40m
Mon, Mar 12
SEA
ONT
2h 27m
Trip: 10 days
8.5ExcellentShow reviews
Overall 8.5 Excellent
Based on 86 reviews
Overall
8.6
Boarding
8.7
Comfort
8.4
Crew
8.9
Entertainment
7.9
Food
8.0
ONT
SEA
Excellent 10.0

The flight left and arrived on time. Overall a great experience with friendly and caring people. Will definitely use them in the near future!

No issues at all

ONT
SEA
Good 6.0

Nice clean planes

No entertainment monitors

ONT
SEA
Excellent 8.3

Good selection of entertainment (movies).

ONT
SEA
Excellent 10.0

On time courteous

ONT
SEA
Excellent 10.0

Fast check-in

Wed, Mar 7
ONT
SEA
4h 45m
Wed, Mar 14
SEA
ONT
5h 44m
Trip: 7 days
7.8GoodShow reviews
Overall 7.8 Good
Based on 16027 reviews
Overall
8.0
Boarding
8.1
Comfort
7.8
Crew
8.4
Entertainment
7.5
Food
7.4
BOS
ATL
Okay 4.0

Comfort Plus allowed us to board early, useful USB ports.

SJC
SLC
Excellent 8.8

Good clean aircraft. Fairly comfortable seats. Even had a power outlet in my row. Not too bad for an aircraft from the late 70s.

for some reason, i had to pay to gate check a bag. It didnt seem like anyone else did while boarding my flight.

SMF
ATL
Excellent 8.6

The crew were so polite and happy!

Those seats! UGH!

BOS
JFK
Excellent 9.3

The volume controls on the tv we’re pretty poor. Was either too loud or too soft with only 5-6 volume settings.

BOS
BNA
Excellent 8.0

Service vey Good. Nice choices. Comfort seating very nice

WiFi awful. Useless.

Tue, Feb 27
ONT
SEA
21h 00m
Fri, Mar 2
SEA
ONT
16h 03m
Trip: 4 days
5.7OkayShow reviews
Overall 5.7 Okay
Based on 33843 reviews
Overall
5.9
Boarding
6.4
Comfort
5.4
Crew
6.8
Entertainment
4.5
Food
4.7
DEN
SFO
Mediocre 2.0

The crew was rude to the passengers. They charge form 9$ to 40$ for seat selection. Charge for a Carry on bag (anything that doesn't fit under your seat). The flights had maintenance issue, hence delayed. I will absolutely avoid traveling with frontier in the future.

TPA
LAS
Okay 4.3

Very reasonable price.

You literally have to pay for even the basic things, including for seats to recline. Cushion on seats thin and seats don't recline. 5hrs flight and No entertainment, no tv, no radio, no complimentary food...they offered a cup of water.

PHL
DEN
Mediocre 2.0

This is actually almost a funny question because Frontier is the worst Airlines well actually that's not true spirit is the worst Airlines the seats are uncomfortable it takes about an hour and a half to just put your bags and baggage drop and then when you get on the plane They don't serve you anything they have no entertainment your crowded in can't move people are rude worst hairlines ever

Every single thing

ORD
RSW
Good 6.0

Crew was super nice

Delayed 3 hours, boarded and was told would be another 30minutes because of mechanical issues.

IAD
SAT
Mediocre 3.6

The crew was helpful and apologetic.

They purposefully understaffed the check in counter, which you have to use. They charge for every little thing, even carry on bags and snacks. The seats might as well be lawn chairs. They are so close together everyone onboard will die from head injuries if there's an accident. I'll fly Southwest from now on.

Show more results

Ontario to Seattle/Tacoma Intl Flight Information

Avg. Flight Duration 2h 34m
Flights Arrive in Seattle/Tacoma Intl
Flights Depart from Ontario
Flight Price $114
Distance 957 miles
Airlines American Airlines, Delta, Alaska Airlines, United, Frontier
*
Prices are per person and are for e–tickets and include all taxes & fees in USD.

We attempt to get accurate prices, however, prices are not guaranteed.

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The fares displayed include all taxes and fees for economy class travel and were found by the provider in the last 72 hours. Seats are limited and may not be available on all flights and days. Fares are subject to change and may not be available on all flights or dates of travel. Some carriers charge additional fees for extra checked bags. Please check the carriers' sites.