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$55+ Cheap flights from Key Largo, FL to St. Louis (STL)

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 12/11. Fares are subject to change and may not be available on all flights or dates of travel.
MIA — STL
Dec 3 — Dec 101
Wed 12/3
Wed 12/10
1 adult, Economy
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Cheapflights Tip: The best prices from Key Largo to Lambert-St Louis are usually found in October or August, booked 62 days in advance, depart on a Thursday or Saturday and return on a Sunday

Find flight deals from Key Largo to St. Louis

Cheapest flights from Key Largo to St. Louis
Explore the most affordable flight options available from Key Largo to St. Louis. Find the lowest fares from popular airlines and budget airlines, with prices last updated on November 3, 2025.

This Frontier deal was found by Cheapflights users on 11/2. 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 12/75:30 amMIA - STL
1 stop5h 17mFrontier
Thu 12/1112:04 pmSTL - MIA
1 stop11h 42mFrontier
Deal found 11/2$124
This Kiwi.com deal was found by Cheapflights users on 11/1. 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.
Mon 12/87:05 amMIA - STL
2 stops52h 09mFrontier
Thu 1/2210:42 amSTL - MIA
1 stop12h 44mFrontier
Deal found 11/1$174
This Kiwi.com deal was found by Cheapflights users on 11/3. 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.
Tue 12/166:00 amMIA - STL
1 stop29h 14mFrontier
Tue 12/2310:48 amSTL - MIA
1 stop7h 42mFrontier
Deal found 11/3$175
This Kiwi.com deal was found by Cheapflights users on 11/2. 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.
Tue 12/26:25 amMIA - STL
1 stop28h 49mFrontier
Tue 12/93:30 pmSTL - MIA
2 stops23h 58mFrontier
Deal found 11/2$189
This Frontier deal was found by Cheapflights users on 11/1. 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 11/246:55 amMIA - STL
1 stop12h 24mFrontier
Wed 12/37:43 pmSTL - MIA
1 stop8h 36mFrontier
Deal found 11/1$190
This Kiwi.com deal was found by Cheapflights users on 11/2. 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 12/103:13 pmMIA - STL
1 stop20h 54mMultiple Airlines
Wed 12/177:43 pmSTL - MIA
2 stops24h 21mMultiple Airlines
Deal found 11/2$192
This Kiwi.com deal was found by Cheapflights users on 11/1. 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 12/125:30 amMIA - STL
1 stop5h 17mFrontier
Sun 12/2110:57 amSTL - MIA
1 stop12h 50mFrontier
Deal found 11/1$197
This Frontier deal was found by Cheapflights users on 11/1. 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 11/246:55 amMIA - STL
1 stop12h 24mFrontier
Sat 12/67:43 pmSTL - MIA
1 stop8h 36mFrontier
Deal found 11/1$208
This Frontier deal was found by Cheapflights users on 11/1. 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.
Tue 11/256:15 amMIA - STL
1 stop13h 43mFrontier
Wed 12/37:43 pmSTL - MIA
1 stop8h 36mFrontier
Deal found 11/1$210
This Frontier deal was found by Cheapflights users on 11/2. 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 11/145:01 amMIA - STL
1 stop12h 00mFrontier
Sun 11/167:45 pmSTL - MIA
1 stop9h 34mFrontier
Deal found 11/2$214

Cheap flight deals from Key Largo to St. Louis

Keep the following information in mind while searching for Key Largo to St. Louis flight deals. Data was last updated November 3, 2025.

Most accurate provider

Mytrip
3 stars

Most trusted provider

Mytrip
3 stars

Round-trip from

$124
(Frontier)

One-way from

$55
(Priceline)

Popular in

March

Cheapest in

October

Average price

$363
Provider with most accurate pricing for Miami-Lambert-St Louis flight deals.
Search Deals
Provider most trusted by Cheapflights users for Miami-Lambert-St Louis flights.
Search Deals
From Key Largo to Lambert-St Louis
Search Deals
One-way flight from Key Largo to Lambert-St Louis
Search Deals
Highest demand for flights based on searches. 14% potential increase in price ($62 potential increase over avg. RT price).
Search Deals
Cheapest flight prices on average. 3% potential price decrease ($12 potential savings vs. average RT price).
Search Deals
Average for round-trip flights in November 2025
Search Deals

Cheapflights Fare Finder

 
Customize your flight search to find flights from Key Largo to St. Louis 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 3, 2025.
Use the filters below to find and compare flights from Key Largo to St. Louis that are best for you.

Fly from

Key Largo

Fly to

St. Louis

Route

Depart

Return

Price

MiamiSt. Louis

MIA - STL

MIASTL

Miami

Thu 1/22

5:35 am-7:50 am

2 stops27h 15m

Lambert-St Louis

Thu 1/29

10:42 am-10:58 am

1 stop23h 16m

$173

MiamiSt. Louis

MIA - STL

MIASTL

Miami

Wed 12/10

3:13 pm-11:07 am

1 stop20h 54m

Lambert-St Louis

Wed 12/17

7:43 pm-9:04 pm

2 stops24h 21m

$192

MiamiSt. Louis

MIA - STL

MIASTL

Miami

Wed 12/10

5:58 pm-11:07 am

1 stop18h 09m

Lambert-St Louis

Wed 12/17

7:43 pm-5:19 am

1 stop8h 36m

$210

MiamiSt. Louis

MIA - STL

MIASTL

Miami

Tue 11/25

6:15 am-6:58 pm

1 stop13h 43m

Lambert-St Louis

Wed 12/3

7:43 pm-5:19 am

1 stop8h 36m

$210

MiamiSt. Louis

MIA - STL

MIASTL

Miami

Thu 12/18

5:30 am-9:40 am

1 stop5h 10m

Lambert-St Louis

Tue 12/23

10:48 am-7:30 pm

1 stop7h 42m

$227

MiamiSt. Louis

MIA - STL

MIASTL

Miami

Thu 11/20

5:30 am-2:29 pm

1 stop9h 59m

Lambert-St Louis

Mon 12/1

7:43 pm-5:10 am

1 stop8h 27m

$230

MiamiSt. Louis

MIA - STL

MIASTL

Miami

Fri 12/12

5:30 am-9:47 am

1 stop5h 17m

Lambert-St Louis

Sun 12/21

10:57 am-7:30 pm

1 stop7h 33m

$234

MiamiSt. Louis

MIA - STL

MIASTL

Miami

Thu 11/20

5:30 am-2:29 pm

1 stop9h 59m

Lambert-St Louis

Sun 11/30

3:14 pm-10:49 am

1 stop18h 35m

$246

MiamiSt. Louis

MIA - STL

MIASTL

Miami

Sat 12/20

10:19 pm-9:40 am

1 stop12h 21m

Lambert-St Louis

Sat 12/27

10:10 pm-12:51 am

2 stops49h 41m

$333

MiamiSt. Louis

MIA - STL

MIASTL

Miami

Tue 12/2

4:55 pm-6:55 pm

Nonstop3h 00m

Lambert-St Louis

Tue 12/9

10:15 am-8:25 pm

2 stops9h 10m

$334

Flights are sorted by cheapest round-trip flights first.

Deals found on 11/3

Showing 1-10 of 19 results
1
2

Best time to book a flight from Key Largo to St. Louis

Have a flexible travel schedule? Discover the best time to fly to St. Louis from Key Largo 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 Key Largo to St. Louis

How far ahead should I book a flight from Key Largo to St. Louis?

Use this chart to determine the optimal time to book a round-trip flight from Key Largo to St. Louis. Price data was last updated on October 31, 2025.

The price you pay for your flight from Key Largo to St. Louis may vary depending on when you book. For the best chance of a lower fare, look to book 62 days in advance of your trip. Fares are likely to increase a fortnight or so before your departure date.

What is the cheapest month to book a flight from Key Largo to St. Louis?

Currently, March is the cheapest month in which you can book a flight from Key Largo to St. Louis (average of $37). Flying from Key Largo to St. Louis in January is currently the most expensive (average of $136). 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 KE9 to STL?

Find hourly flight availability from Key Largo to St. Louis. Discover flight options and departure times throughout the day, allowing you to choose a departure time that suits your schedule. Data last updated November 3, 2025.

One of the essential ways to save on airfare from Key Largo to St. Louis is to remain as flexible as possible. Flights that are in the evening tend to be the most expensive. A flight at noon could potentially save you up to 20% on airfare.

What is the cheapest day to fly from Key Largo to St. Louis?

Use this chart to determine the cheapest time to fly round-trip from Key Largo to St. Louis. Price data was last updated on December 16, 2024.

Travelers seeking maximum savings on their Key Largo to St. Louis flight should consider departing on Tuesday at noon when fares are most often at their lowest. Monday evenings flights should be avoided if possible as fares are typically the most expensive at this time.

Weekly flight availability from Key Largo to St. Louis

Explore weekly flight availability from Key Largo to St. Louis. 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 3, 2025.

The most flights from KE9 to STL are scheduled on a Monday (5 on average). You will have fewer flight options on Saturday, which is when the least amount of flights are scheduled (1 on average).

Reviews of airlines servicing St. Louis

Get insights into the airlines that provide service to St. Louis. 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 St. Louis. Reviews last updated November 3, 2025.
See what other customers who have flown with Southwest, Delta, and American Airlines from Key Largo to St. Louis 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
4,238 reviews

Comfort

8.0

Food

7.0

Entertainment

7.5

Crew

8.6

Overall

8.0

Boarding

8.1

Reviews

1 / 20
2.0
Mediocre

Mike,Aug 2025

OKC - AUS

AC was not adequate, even on a night flight. WiFi subpar even for the airlines
Southwest
8.0
Very good
4,238 reviews
Southwest
8.0
Very good
4,238 reviews

Comfort

8.0

Food

7.0

Entertainment

7.5

Crew

8.6

Overall

8.0

Boarding

8.1

Reviews

1 / 20
2.0
Mediocre

Mike,Aug 2025

OKC - AUS

AC was not adequate, even on a night flight. WiFi subpar even for the airlines
Delta
7.9
Good
8,002 reviews
Southwest
8.0
Very good
4,238 reviews

Comfort

8.0

Food

7.0

Entertainment

7.5

Crew

8.6

Overall

8.0

Boarding

8.1

Reviews

1 / 20
2.0
Mediocre

Mike,Aug 2025

OKC - AUS

AC was not adequate, even on a night flight. WiFi subpar even for the airlines
American Airlines
7.2
Good
11,038 reviews
Southwest
8.0
Very good
4,238 reviews

Comfort

8.0

Food

7.0

Entertainment

7.5

Crew

8.6

Overall

8.0

Boarding

8.1

Reviews

1 / 20
2.0
Mediocre

Mike,Aug 2025

OKC - AUS

AC was not adequate, even on a night flight. WiFi subpar even for the airlines
Spirit Airlines
6.3
Okay
8,115 reviews
Southwest
8.0
Very good
4,238 reviews

Comfort

8.0

Food

7.0

Entertainment

7.5

Crew

8.6

Overall

8.0

Boarding

8.1

Reviews

1 / 20
2.0
Mediocre

Mike,Aug 2025

OKC - AUS

AC was not adequate, even on a night flight. WiFi subpar even for the airlines
Frontier
5.8
Fair
3,117 reviews
Southwest
8.0
Very good
4,238 reviews

Comfort

8.0

Food

7.0

Entertainment

7.5

Crew

8.6

Overall

8.0

Boarding

8.1

Reviews

1 / 20
2.0
Mediocre

Mike,Aug 2025

OKC - AUS

AC was not adequate, even on a night flight. WiFi subpar even for the airlines

Related info for your journey

Find useful and relevant information for your journey from Key Largo to St. Louis. 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 into for flights to St. Louis from Key Largo?

    If you book a flight to St. Louis from Key Largo, you will be flying to Lambert-St Louis, which is the city’s only airport. Lambert-St Louis (STL) is located 12.7 mi from the center of St. Louis. There are 4 flights from Key Largo to Lambert-St Louis per day from 5 different airlines.

  • How popular is this Key Largo to St. Louis flight route?

    Flights from Key Largo to Lambert-St Louis have been viewed 12 times in the past calendar month.

  • How long is the flight from Key Largo to St. Louis?

    Airlines like Frontier fly from Key Largo to St. Louis in about 27h 15m. The time it takes to get you to your destination can typically vary by up to . The distance from Key Largo to St. Louis is about 1069 mi.

  • What are the most reliable airlines from Key Largo to St. Louis?

    Before booking your flight to St. Louis from Key Largo, check out the most reliable airlines to get you to your destination on time: Royal Air Maroc (78%), American Airlines (71%), GOL( 70%).

  • What are the cheapest flights from Key Largo to St. Louis?

    Looking at all options, your cheapest flight can be booked for $106. While the most popular route (Miami - Lambert-St Louis) can be booked for $162 on average, our data indicates $266 when flying from Key Largo to St. Louis.

  • Can I find deals for flights from Key Largo to St. Louis that include hotel bookings?

    Yes. In addition to deals on Key Largo to St. Louis flights, Cheapflights offers vacation packages that include both flights and hotel.

  • How can I find direct flights from Key Largo to St. Louis?

    After entering your origin and destination, apply the non-stop filter on the search result page to find direct flights from Key Largo to St. Louis.

  • Can I find deals for business class flights from Key Largo to St. Louis?

    Yes. Cheapflights offers flight deals from Key Largo to St. Louis 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 Key Largo to St. Louis?

    Currently, March is the cheapest month in which you can book a flight from Key Largo to St. Louis (average of $37). Flying from Key Largo to St. Louis in January is currently the most expensive (average of $136). 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 St. Louis?

Book flights to St. Louis if you plan to visit one of these locations
Edwardsville
O'Fallon
Fairview Heights
Maryland Heights
Collinsville
Eureka
Glencoe
St. Peters
Chesterfield
Alton
Farmington
Festus

Browse thousands of different options on Cheapflights for your next trip

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Top 5 airlines flying from Key Largo to St. Louis

Discover the top 5 airlines that operate flights from Key Largo to St. Louis. 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 3, 2025.
AirlineCheapestAverageFlexibilityOn-time
Spirit AirlinesCheapest$80Average$173FlexibilityNo cancel feeOn-time65%
FrontierCheapest$164Average$260FlexibilityNo cancel feeOn-time62%
SouthwestCheapest$186Average$378FlexibilityNo cancel feeOn-time63%
DeltaCheapest$196Average$333FlexibilityNo cancel feeOn-timeN/A
American AirlinesCheapest$212Average$401FlexibilityNo cancel feeOn-time71%

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