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$63+ Cheap flights from Ontario (ONT) to Chicago (CHI)

This is the cheapest one-way flight price found by a Cheapflights user in the last 72 hours by searching for a flight departing on 1/16. Fares are subject to change and may not be available on all flights or dates of travel.
ONT — CHI
Dec 22 — Dec 291
Mon 12/22
Mon 12/29
1 adult, Economy
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Find cheap flights from Ontario to Chicago with Cheapflights

1. Tell us where you want to go

Enter your travel information like dates, passengers, trip type (one-way or round trip), and preferred cabin class then click “Find deals”

2. Select your favorite providers

We find the providers serving your travel needs. Choose up to four travel providers to compare side-by-side for flights, hotels, or car rentals.

3. Compare prices and book

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Cheapflights Tip: The best prices from Ontario to Chicago are usually found in November or June, booked 88 days in advance, depart on a Wednesday or Tuesday and return on a Tuesday

Cheap flight deals from Ontario to Chicago

Discover tips and strategies to find the most affordable flight options for your journey from Ontario (ONT) to Chicago (CHI). Learn about various techniques such as flexible date searches, comparing prices across and setting up price alerts. Use these methods to find the cheapest flights available for your travel needs. Data last updated November 22, 2025.

Most accurate provider

Justfly.com
3 stars

Most trusted provider

Justfly.com
3 stars

Round-trip from

$171
(Kiwi.com)

One-way from

$63
(Trip.com)

Popular in

December

Cheapest in

November

Average price

$310

Good round-trip deal

$336 or less

Good one-way deal

$110 or less
Provider with most accurate pricing for Ontario-Chicago (CHI) flight deals.
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Provider most trusted by Cheapflights users for Ontario-Chicago (CHI) flights.
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From Ontario to Chicago (CHI)
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One-way flight from Ontario to Chicago (CHI)
Search Deals
Highest demand for flights based on searches. 6% potential increase in price ($24 potential increase over avg. RT price).
Search Deals
Cheapest flight prices on average. 3% potential price decrease ($11 potential savings vs. average RT price).
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Average for round-trip flights in November 2025
Search Deals
Price to beat on a round-trip flight from Ontario to Chicago (CHI).
Search Deals
Price to beat on a one-way flight from Ontario to Chicago (CHI).
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Find flight deals from Ontario to Chicago

Cheapest flights from Ontario to Chicago
Explore the most affordable flight options available from Ontario to Chicago. Find the lowest fares from popular airlines and budget airlines, with prices last updated on November 22, 2025.

This Kiwi.com deal was found by Cheapflights users on 11/22. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 12/116:15 amONT - ORD
1 stop27h 27mFrontier
Mon 12/1512:59 pmORD - ONT
1 stop10h 18mFrontier
Deal found 11/22$176
This Frontier deal was found by Cheapflights users on 11/21. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 12/218:19 amONT - ORD
1 stop10h 20mFrontier
Wed 12/319:34 pmORD - ONT
1 stop13h 19mFrontier
Deal found 11/21$184
This Kiwi.com deal was found by Cheapflights users on 11/21. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 12/106:15 amONT - MDW
2 stops29h 49mFrontier
Mon 12/1512:35 pmMDW - ONT
1 stop24h 52mFrontier
Deal found 11/21$195
This CheapOair deal was found by Cheapflights users on 11/19. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 12/246:20 pmONT - ORD
1 stop23h 01mFrontier
Thu 1/1510:41 pmORD - ONT
1 stop10h 56mFrontier
Deal found 11/19$197
This CheapOair deal was found by Cheapflights users on 11/21. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 12/63:20 pmONT - MDW
1 stop17h 48mFrontier
Mon 12/812:35 pmMDW - ONT
1 stop6h 57mFrontier
Deal found 11/21$203
This Frontier deal was found by Cheapflights users on 11/21. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 12/412:04 pmONT - ORD
1 stop10h 08mFrontier
Mon 12/87:00 amORD - ONT
1 stop9h 25mFrontier
Deal found 11/21$203
This Frontier deal was found by Cheapflights users on 11/21. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 12/153:20 pmONT - ORD
1 stop6h 52mFrontier
Wed 12/319:34 pmORD - ONT
1 stop13h 19mFrontier
Deal found 11/21$204
This Flightnetwork deal was found by Cheapflights users on 11/22. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Flightnetwork is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 12/63:20 pmONT - MDW
1 stop17h 48mFrontier
Sun 12/142:01 pmMDW - ONT
1 stop28h 32mFrontier
Deal found 11/22$207
This Frontier deal was found by Cheapflights users on 11/21. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 12/123:20 pmONT - ORD
1 stop6h 52mFrontier
Mon 12/1512:59 pmORD - ONT
1 stop10h 18mFrontier
Deal found 11/21$207
This Kiwi.com deal was found by Cheapflights users on 11/21. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 12/106:15 amONT - MDW
2 stops29h 49mFrontier
Sun 12/142:01 pmMDW - ONT
1 stop28h 32mFrontier
Deal found 11/21$211
This CheapOair deal was found by Cheapflights users on 11/19. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure CheapOair is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 12/266:45 amONT - ORD
1 stop15h 27mFrontier
Thu 1/17:57 pmORD - ONT
1 stop13h 22mFrontier
Deal found 11/19$215
This Kiwi.com deal was found by Cheapflights users on 11/21. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 12/52:05 pmONT - ORD
1 stop7h 37mMultiple Airlines
Tue 12/167:20 amORD - ONT
2 stops39h 57mMultiple Airlines
Deal found 11/21$216

Cheapflights Fare Finder

 
Customize your flight search to find flights from Ontario to Chicago that fit within your specific budget. Explore options based on user searches and filter the results based on your desired price range. Find flights that match your budget for a cost-effective journey. Over the last 7 days, Cheapflights users made 2,558,603 searches. Data last updated November 22, 2025.
Use the filters below to find and compare flights from Ontario to Chicago that are best for you.

Fly from

Ontario

Fly to

Chicago

Route

Depart

Return

Price

OntarioChicago

ONT - MDW

ONTMDW

Ontario

Wed 12/10

6:15 am-2:04 pm

2 stops29h 49m

Chicago Midway

Mon 12/15

12:35 pm-11:27 am

1 stop24h 52m

$195

OntarioChicago

ONT - MDW

ONTMDW

Ontario

Thu 1/15

8:02 am-5:20 pm

1 stop7h 18m

Chicago Midway

Fri 1/16

9:09 pm-10:59 pm

1 stop27h 50m

$252

OntarioChicago

ONT - MDW

ONTMDW

Ontario

Sat 1/24

10:30 pm-9:53 am

1 stop9h 23m

Chicago Midway

Wed 1/28

12:48 pm-9:05 pm

1 stop10h 17m

$265

OntarioChicago

ONT - MDW

ONTMDW

Ontario

Fri 1/16

6:10 am-7:54 pm

1 stop11h 44m

Chicago Midway

Mon 1/19

9:09 pm-3:07 pm

1 stop19h 58m

$292

OntarioChicago

ONT - ORD

ONTORD

Ontario

Fri 1/30

7:30 am-9:52 pm

2 stops12h 22m

Chicago O'Hare Intl

Mon 2/2

2:20 pm-10:51 pm

1 stop10h 31m

$300

OntarioChicago

ONT - ORD

ONTORD

Ontario

Thu 2/5

7:30 am-9:43 pm

2 stops12h 13m

Chicago O'Hare Intl

Sat 2/7

7:30 am-1:56 pm

1 stop8h 26m

$300

OntarioChicago

ONT - MDW

ONTMDW

Ontario

Fri 1/23

10:30 pm-12:46 pm

2 stops12h 16m

Chicago Midway

Wed 1/28

12:48 pm-9:05 pm

1 stop10h 17m

$318

OntarioChicago

ONT - ORD

ONTORD

Ontario

Wed 1/7

11:53 am-11:50 pm

1 stop9h 57m

Chicago O'Hare Intl

Mon 1/12

3:35 pm-11:56 pm

1 stop10h 21m

$321

OntarioChicago

ONT - ORD

ONTORD

Ontario

Fri 1/30

6:00 am-5:10 pm

1 stop9h 10m

Chicago O'Hare Intl

Mon 2/2

8:00 am-3:08 pm

1 stop9h 08m

$324

OntarioChicago

ONT - ORD

ONTORD

Ontario

Sun 12/14

12:40 pm-11:59 pm

1 stop9h 19m

Chicago O'Hare Intl

Wed 2/18

6:45 pm-11:53 pm

1 stop7h 08m

$332

Flights are sorted by cheapest round-trip flights first.

Deals found on 11/21

Showing 1-10 of 42 results
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Compare providers for flights from Ontario to Chicago

Provider information is updated monthly. Please note that these providers often have deals for this flight, but the availability may vary on a day-by-day basis on Cheapflights.
Use the table below to compare price accuracy, trust ratings, and cancellation policies for each provider offering flight deals from Ontario to Chicago in November.
ProviderPrice AccuracyTrust Score*
ExpediaPrice Accuracy2 starsTrust Score*3 stars
eDreamsPrice Accuracy3 starsTrust Score*3 stars
FlightHubPrice Accuracy3 starsTrust Score*1 star
Justfly.comPrice Accuracy3 starsTrust Score*3 stars
MytripPrice Accuracy3 starsTrust Score*3 stars

*The Trust Score is based on feedback from users after their booking experience. It measures overall satisfaction, helping us identify issues like hidden fees, problems during the ticketing process, and the quality of customer service. This score is our best indicator of the provider's quality and reliability.

  • Most accurate provider: When it comes to deals on Ontario-Chicago flights, users find the pricing of Justfly.com to be most consistent on Cheapflights vs. Justfly.com Users can find the same prices on Ontario-Chicago flight deals on Cheapflights vs. Justfly.com >95% of the time. Price accuracy is based on data collected from Ontario-Chicago flight searches over the past month and is updated monthly.
  • Most trusted provider: When it comes to deals on Ontario-Chicago flights, Cheapflights users trust Justfly.com the most. Justfly.com has received a user feedback score of 3 out of 3 stars (3 being the best), meaning they have been trusted the most by Cheapflights users looking for Ontario-Chicago flight deals. Provider user feedback score is based on Cheapflights searches over the past month and is updated monthly.

Best time to book a flight from Ontario to Chicago

Have a flexible travel schedule? Discover the best time to fly to Chicago from Ontario with our price prediction graph.
Estimated round-trip price
Rates are based on past data. Find the cheapest month and day to book your flight based on your travel requirements, then search for cheap deals.

Cheapflights Insights

Everything you need to know about your flight from Ontario to Chicago

How far ahead should I book a flight from Ontario to Chicago?

Use this chart to determine the optimal time to book a round-trip flight from Ontario to Chicago. Price data was last updated on November 21, 2025.

The best time to book flights from Ontario to Chicago is 88 days before your desired departure date. The cost of your flight will likely increase significantly if you book two weeks in advance of your flight.

What is the cheapest month to book a flight from Ontario to Chicago?

Currently, March is the cheapest month in which you can book a flight from Ontario to Chicago (average of $77). Flying from Ontario to Chicago in October is currently the most expensive (average of $147). There are several factors that can impact the price of a flight, so comparing airlines, departure airports and flight times can provide users with more options.

What is the cheapest time of day to fly from ONT to CHI?

Find hourly flight availability from Ontario to Chicago. Discover flight options and departure times throughout the day, allowing you to choose a departure time that suits your schedule. Data last updated November 22, 2025.

Unlike in the morning, when flights are generally more expensive, you can save up to 49% on flights from Ontario to Chicago by exploring options for tickets in the afternoon.

What is the cheapest day to fly from Ontario to Chicago?

Use this chart to determine the cheapest time to fly round-trip from Ontario to Chicago. Price data was last updated on November 2, 2025.

Travelers seeking maximum savings on their Ontario to Chicago flight should consider departing on Thursday at noon when fares are most often at their lowest. Sunday at noon flights should be avoided if possible as fares are typically the most expensive at this time.

Weekly flight availability from Ontario to Chicago

Explore weekly flight availability from Ontario to Chicago. Discover flights operating on different days of the week, giving you the flexibility to choose a travel day that best fits your plans. Compare info to find the most convenient option for your journey. Data last updated November 22, 2025.

The most flights from ONT to CHI are scheduled on a Monday (2 on average). You will have fewer flight options on Tuesday, which is when the least amount of flights are scheduled (1 on average).

How much does it cost to fly round-trip from Ontario to Chicago?

The best insider tips for Ontario to Chicago flights

Snippets provided in this section are AI-generated based on a summarization of Cheapflights-commissioned articles. The articles are presented as-is, for general informational purposes only, and may not be up-to-date. The opinions contained in the articles are original to the author and reflect their authentic experience, which may vary significantly from the experience of others.
Cheapflights partnered with top experts to bring you the best recommendations for your Ontario to Chicago trip
Airports
ONT

For business travelers, ONT offers a smooth security process, often quicker than LAX, making it ideal for weekday commutes.

Read more about ONTby Bill Fink
MDW

Use the Orange Line train for a quick, budget-friendly trip from MDW to downtown Chicago in under 30 minutes.

Read more about MDWby Ramsey Qubein
Our travel experts
Ramsey Qubein

Ramsey Qubein

Expert on MDW

Ramsey Qubein

Ramsey Qubein

An avid traveler and aviation expert who has visited 173 countries, all 50 states and seven continents, Ramsey Qubein flies nearly 400,000 miles a year. As a North Carolina-based freelance journalist for publications including Conde Nast Traveler, Forbes, USA Today and Bloomberg among others, he explores the latest trends in aviation, hospitality, cruises and business.

Read more
Bill Fink

Bill Fink

Expert on ONT

Bill Fink

Bill Fink

Bill is an award-winning travel writer with extensive credits covering airlines and the aviation industry for publications including AARP, AFAR, The Points Guy and Yahoo. Based in Portland, Oregon, Bill has traveled to more than 75 countries - and been late for his flight in most of them. He once achieved top-level frequent flier status for all of American, Delta and United Airlines during a single year.

Read more

Reviews of airlines servicing Chicago

Get insights into the airlines that provide service to Chicago. Read reviews, discover amenities, and learn about the overall travel experience offered by airlines. Use this information to make informed decisions when choosing an airline for your flight to Chicago. Reviews last updated November 22, 2025.
See what other customers who have flown with Southwest, Delta, and United Airlines from Ontario to Chicago have to say. You can also see how each airline compares in terms of entertainment options, comfort, food, crew/service, and boarding process.
Southwest
8.0
Very good
4,253 reviews

Entertainment

7.5

Boarding

8.1

Food

7.0

Comfort

8.0

Crew

8.6

Overall

8.0

Reviews

1 / 20
8.0
Excellent

Walter,Aug 2025

OAK - SAN

Dozens of flights and I've never seen a row's beverages forgotten. I even went back and asked the attendant to check on them and nothing. I really hope it didn't have something to do with the Black mother with her kid in the row. Otherwise it was a typical Southwest flight, rapid boarding, tolerable leg room.
Southwest
8.0
Very good
4,253 reviews
Southwest
8.0
Very good
4,253 reviews

Entertainment

7.5

Boarding

8.1

Food

7.0

Comfort

8.0

Crew

8.6

Overall

8.0

Reviews

1 / 20
8.0
Excellent

Walter,Aug 2025

OAK - SAN

Dozens of flights and I've never seen a row's beverages forgotten. I even went back and asked the attendant to check on them and nothing. I really hope it didn't have something to do with the Black mother with her kid in the row. Otherwise it was a typical Southwest flight, rapid boarding, tolerable leg room.
Delta
7.9
Good
8,000 reviews
Southwest
8.0
Very good
4,253 reviews

Entertainment

7.5

Boarding

8.1

Food

7.0

Comfort

8.0

Crew

8.6

Overall

8.0

Reviews

1 / 20
8.0
Excellent

Walter,Aug 2025

OAK - SAN

Dozens of flights and I've never seen a row's beverages forgotten. I even went back and asked the attendant to check on them and nothing. I really hope it didn't have something to do with the Black mother with her kid in the row. Otherwise it was a typical Southwest flight, rapid boarding, tolerable leg room.
United Airlines
7.4
Good
9,036 reviews
Southwest
8.0
Very good
4,253 reviews

Entertainment

7.5

Boarding

8.1

Food

7.0

Comfort

8.0

Crew

8.6

Overall

8.0

Reviews

1 / 20
8.0
Excellent

Walter,Aug 2025

OAK - SAN

Dozens of flights and I've never seen a row's beverages forgotten. I even went back and asked the attendant to check on them and nothing. I really hope it didn't have something to do with the Black mother with her kid in the row. Otherwise it was a typical Southwest flight, rapid boarding, tolerable leg room.
American Airlines
7.2
Good
11,047 reviews
Southwest
8.0
Very good
4,253 reviews

Entertainment

7.5

Boarding

8.1

Food

7.0

Comfort

8.0

Crew

8.6

Overall

8.0

Reviews

1 / 20
8.0
Excellent

Walter,Aug 2025

OAK - SAN

Dozens of flights and I've never seen a row's beverages forgotten. I even went back and asked the attendant to check on them and nothing. I really hope it didn't have something to do with the Black mother with her kid in the row. Otherwise it was a typical Southwest flight, rapid boarding, tolerable leg room.
Frontier
5.8
Fair
3,100 reviews
Southwest
8.0
Very good
4,253 reviews

Entertainment

7.5

Boarding

8.1

Food

7.0

Comfort

8.0

Crew

8.6

Overall

8.0

Reviews

1 / 20
8.0
Excellent

Walter,Aug 2025

OAK - SAN

Dozens of flights and I've never seen a row's beverages forgotten. I even went back and asked the attendant to check on them and nothing. I really hope it didn't have something to do with the Black mother with her kid in the row. Otherwise it was a typical Southwest flight, rapid boarding, tolerable leg room.

Related info for your journey

Find useful and relevant information for your journey from Ontario to Chicago. Access travel guides, tips, and recommendations to enhance your travel experience. Get information about local attractions, weather, transportation options, and more.

  • What airport do you fly from for flights from Ontario to Chicago?

    Ontario (ONT) is the airport you will fly out of if you book a flight from Ontario to Chicago. You should not have trouble finding flights to Chicago from Ontario; the airport handles an average of 1 outbound flight to Chicago per day. You should also have plenty of airline options to choose from since 5 airlines have flights from the Ontario airport to Chicago. It is only a 3.1 mi journey to Ontario (ONT) from Ontario’s city center.

  • How long is the flight from Ontario to Chicago?

    Frontier, Delta, and Alaska Airlines can get you from Ontario to Chicago in just under 9h 23m. Your travel time can differ by up to 20h 26m. The distance from Ontario to Chicago is about 1701 mi. When browsing for deals, the options you’ll see will be for both nonstop flights and flights with stops.

  • What are the cheapest airlines flying from Ontario to Chicago round-trip?

    Cheapflights users have booked flights from Ontario to Chicago round-trip from $110. Other airlines that can offer you cheap pricing are United Airlines, from $227, and Southwest, from $237. These flights start at 70% lower than the current average price 3 months from now.

  • What are the most popular routes from Ontario to Chicago?

    Most travelers choose Ontario - Chicago O'Hare Intl, Ontario - Chicago Midway or Ontario - Chicago Greater Rockford when deciding on the best route from Ontario to Chicago.

  • What are the cheapest flights from Ontario to Chicago?

    On average you can expect to pay $671 for a flight from Ontario to Chicago. The cheapest flight overall is $183 while the most popular route, (Ontario - Chicago O'Hare Intl) is currently priced at $182.

  • Can I find deals for flights from Ontario to Chicago that include hotel bookings?

    Yes. In addition to deals on Ontario to Chicago flights, Cheapflights offers vacation packages that include both flights and hotel.

  • How can I find direct flights from Ontario to Chicago?

    After entering your origin and destination, apply the non-stop filter on the search result page to find direct flights from Ontario to Chicago.

  • Can I find deals for business class flights from Ontario to Chicago?

    Yes. Cheapflights offers flight deals from Ontario to Chicago by cabin class. In addition to browsing deals, you can also filter by cabin class on the search results page after making a search.

  • What is the cheapest month to book a flight from Ontario to Chicago?

    Currently, March is the cheapest month in which you can book a flight from Ontario to Chicago (average of $77). Flying from Ontario to Chicago in October is currently the most expensive (average of $147). There are several factors that can impact the price of a flight, so comparing airlines, departure airports and flight times can provide users with more options.

See more FAQs

Traveling to a place near Chicago?

Book flights to Chicago if you plan to visit one of these locations
Lansing
Hammond
Porter
Benton Harbor
Merrillville

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Alternative routes for Ontario to Chicago

See prices for flight routes from nearby airports that may be better suited for you.
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Top 5 airlines flying from Ontario to Chicago

Discover the top 5 airlines that operate flights from Ontario to Chicago. Compare their services, reliability, and customer satisfaction ratings to choose the airline that best suits your travel preferences and needs. Over the last 7 days, Cheapflights users made 2,558,603 searches. Data last updated November 22, 2025.
AirlineCheapestAverageFlexibilityOn-time
FrontierCheapest$110Average$217FlexibilityNo cancel feeOn-time62%
United AirlinesCheapest$227Average$393FlexibilityNo cancel feeOn-time69%
SouthwestCheapest$237Average$423FlexibilityNo cancel feeOn-time63%
American AirlinesCheapest$246Average$474FlexibilityNo cancel feeOn-time71%
DeltaCheapest$256Average$381FlexibilityNo cancel feeOn-timeN/A

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