HomeSearch by dateVacation packagesHotelsFlight dealsCar rentalTravel tips & news
Key Largo

$65+ Cheap flights from St. Louis (STL) to Key Largo, FL

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 1/18. Fares are subject to change and may not be available on all flights or dates of travel.
STL — MIA
Oct 16 — Oct 231
Thu 10/16
Thu 10/23
1 adult, Economy
We work with more than 300 partners to bring you better travel deals

Find cheap flights from St. Louis to Key Largo 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

Review each provider’s pricing and select the best option for you! Book through your favorite provider’s website for a seamless experience.

Cheapflights Tip: The best prices from Lambert-St Louis to Key Largo are usually found in August or September, booked 33 days in advance, depart on a Wednesday or Sunday and return on a Saturday

Cheap flight deals from St. Louis to Key Largo

Keep the following information in mind while searching for St. Louis to Key Largo flight deals. Data was last updated September 16, 2025.

Round-trip from

$168
(Frontier)

One-way from

$65
(American Airlines)

Popular in

March

Cheapest in

August

Average price

$344
From Lambert-St Louis to Key Largo
Search Deals
One-way flight from Lambert-St Louis to Key Largo
Search Deals
Highest demand for flights based on searches. 10% potential increase in price ($45 potential increase over avg. RT price).
Search Deals
Cheapest flight prices on average. 2% potential price decrease ($12 potential savings vs. average RT price).
Search Deals
Average for round-trip flights in September 2025
Search Deals

Find flight deals from St. Louis to Key Largo

Cheapest flights from St. Louis to Key Largo
Explore the most affordable flight options available from St. Louis to Key Largo. Find the lowest fares from popular airlines and budget airlines, with prices last updated on September 16, 2025.

This Frontier deal was found by Cheapflights users on 9/13. 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.
Sat 11/87:45 pmSTL - MIA
1 stop9h 34mFrontier
Sun 11/168:25 amMIA - STL
1 stop9h 57mFrontier
Deal found 9/13$168
This American Airlines deal was found by Cheapflights users on 9/15. 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 American Airlines is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 10/145:23 amSTL - MIA
Nonstop2h 47mAmerican Airlines
Tue 10/2110:01 pmMIA - STL
Nonstop2h 55mAmerican Airlines
Deal found 9/15$169
This Frontier deal was found by Cheapflights users on 9/14. 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 10/247:52 pmSTL - MIA
1 stop9h 27mFrontier
Fri 10/315:05 amMIA - STL
1 stop11h 52mFrontier
Deal found 9/14$182
This Priceline deal was found by Cheapflights users on 9/15. 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 Priceline is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 10/314:52 pmSTL - MIA
1 stop6h 42mFrontier
Sun 11/25:05 amMIA - STL
1 stop6h 07mFrontier
Deal found 9/15$183
This Booking.com deal was found by Cheapflights users on 9/16. 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 Booking.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 10/257:52 pmSTL - MIA
1 stop9h 27mFrontier
Sun 11/25:00 amMIA - STL
1 stop28h 07mFrontier
Deal found 9/16$185
This Priceline deal was found by Cheapflights users on 9/15. 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 Priceline is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 10/2310:17 amSTL - MIA
1 stop6h 16mFrontier
Sun 10/265:15 amMIA - STL
1 stop6h 22mFrontier
Deal found 9/15$188
This Frontier deal was found by Cheapflights users on 9/15. 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.
Sat 10/47:55 pmSTL - MIA
2 stops13h 45mFrontier
Thu 10/95:15 amMIA - STL
1 stop6h 22mFrontier
Deal found 9/15$190
This Frontier deal was found by Cheapflights users on 9/15. 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 10/308:40 pmSTL - MIA
2 stops12h 31mFrontier
Thu 11/65:01 amMIA - STL
1 stop6h 11mFrontier
Deal found 9/15$191
This Priceline deal was found by Cheapflights users on 9/14. 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 Priceline is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 10/298:40 pmSTL - MIA
1 stop8h 39mFrontier
Sun 11/25:05 amMIA - STL
1 stop6h 07mFrontier
Deal found 9/14$193
This Booking.com deal was found by Cheapflights users on 9/16. 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 Booking.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 9/267:55 pmSTL - MIA
1 stop27h 49mFrontier
Mon 9/295:30 amMIA - STL
1 stop10h 34mFrontier
Deal found 9/16$194
This Delta deal was found by Cheapflights users on 9/15. 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 Delta is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Tue 10/146:00 amSTL - MIA
1 stop4h 04mDelta
Tue 10/2112:09 pmMIA - STL
1 stop4h 46mDelta
Deal found 9/15$197

Cheapflights Fare Finder

 
Customize your flight search to find flights from St. Louis to Key Largo 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 September 16, 2025.
Use the filters below to find and compare flights from St. Louis to Key Largo that are best for you.

Fly from

St. Louis

Fly to

Key Largo

Route

Depart

Return

Price

St. LouisMiami

STL - MIA

STLMIA

Lambert-St Louis

Sat 11/8

5:15 pm-12:29 am

1 stop6h 14m

Miami

Sat 11/15

8:05 am-1:51 pm

1 stop6h 46m

$197

St. LouisMiami

STL - MIA

STLMIA

Lambert-St Louis

Tue 10/14

1:30 pm-6:34 pm

1 stop4h 04m

Miami

Tue 10/21

6:00 am-10:26 am

1 stop5h 26m

$197

St. LouisMiami

STL - MIA

STLMIA

Lambert-St Louis

Sat 12/6

5:12 pm-12:46 am

1 stop6h 34m

Miami

Wed 12/10

7:00 am-10:41 am

1 stop4h 41m

$197

St. LouisMiami

STL - MIA

STLMIA

Lambert-St Louis

Mon 11/24

11:44 am-6:20 pm

1 stop5h 36m

Miami

Fri 11/28

6:00 am-10:04 am

1 stop5h 04m

$197

St. LouisMiami

STL - MIA

STLMIA

Lambert-St Louis

Sat 10/11

5:25 pm-12:29 am

1 stop6h 04m

Miami

Sat 10/18

6:00 am-9:15 am

1 stop4h 15m

$198

St. LouisMiami

STL - MIA

STLMIA

Lambert-St Louis

Wed 12/24

6:00 am-12:56 pm

1 stop5h 56m

Miami

Tue 12/30

7:27 pm-11:39 pm

1 stop5h 12m

$218

St. LouisMiami

STL - MIA

STLMIA

Lambert-St Louis

Tue 2/10

12:30 pm-9:02 pm

1 stop7h 32m

Miami

Wed 2/18

7:00 am-10:50 am

1 stop4h 50m

$219

St. LouisMiami

STL - MIA

STLMIA

Lambert-St Louis

Thu 11/13

9:21 am-5:18 pm

1 stop6h 57m

Miami

Mon 11/24

6:23 pm-9:58 pm

1 stop4h 35m

$238

St. LouisMiami

STL - MIA

STLMIA

Lambert-St Louis

Sat 11/1

5:15 pm-11:20 am

2 stops17h 05m

Miami

Fri 11/7

8:30 am-1:22 pm

1 stop5h 52m

$265

St. LouisMiami

STL - MIA

STLMIA

Lambert-St Louis

Mon 11/24

3:15 pm-10:05 pm

2 stops5h 50m

Miami

Tue 12/2

7:40 am-11:25 am

1 stop4h 45m

$274

Flights are sorted by cheapest round-trip flights first.

Deals found on 9/14

Showing 1-10 of 22 results
1
2
3

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

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

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

Use this chart to determine the optimal time to book a round-trip flight from St. Louis to Key Largo. Price data was last updated on September 12, 2025.

To ensure you get the cheapest price possible for a flight from St. Louis to Key Largo, you should look to book at least 33 days in advance of your intended travel date. The price of your flight may increase if you delay and leave booking until a week or so before departure.

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

Currently, September is the cheapest month in which you can book a flight from St. Louis to Key Largo (average of $232). Flying from St. Louis to Key Largo in March is currently the most expensive (average of $289). 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 STL to KE9?

Find hourly flight availability from St. Louis to Key Largo. Discover flight options and departure times throughout the day, allowing you to choose a departure time that suits your schedule. Data last updated September 16, 2025.

Regardless of the time of day you decide to fly, the ticket price will remain around the same. Book flights from St. Louis to Key Largo as you normally would.

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

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

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

Weekly flight availability from St. Louis to Key Largo

Explore weekly flight availability from St. Louis to Key Largo. 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 September 16, 2025.

The most flights from STL to KE9 are scheduled on a Monday (3 on average). You will have fewer flight options on Saturday, which is when the least amount of flights are scheduled (2 on average).

Reviews of airlines servicing Key Largo

Get insights into the airlines that provide service to Key Largo. 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 Key Largo. Reviews last updated September 16, 2025.
Peruse reviews from past customers who have flown with Southwest, Delta, and American Airlines from St. Louis to Key Largo to help guide your decision. You can also see how each airline stacks up in terms of entertainment options, comfort, food, crew/service, and boarding process.
Southwest
8.0
Very good
4,242 reviews

Entertainment

7.5

Crew

8.6

Boarding

8.1

Food

7.0

Comfort

8.0

Overall

8.0

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
4,242 reviews
Southwest
8.0
Very good
4,242 reviews

Entertainment

7.5

Crew

8.6

Boarding

8.1

Food

7.0

Comfort

8.0

Overall

8.0

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
8.0
Very good
7,957 reviews
Southwest
8.0
Very good
4,242 reviews

Entertainment

7.5

Crew

8.6

Boarding

8.1

Food

7.0

Comfort

8.0

Overall

8.0

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
10,000 reviews
Southwest
8.0
Very good
4,242 reviews

Entertainment

7.5

Crew

8.6

Boarding

8.1

Food

7.0

Comfort

8.0

Overall

8.0

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
8,019 reviews
Southwest
8.0
Very good
4,242 reviews

Entertainment

7.5

Crew

8.6

Boarding

8.1

Food

7.0

Comfort

8.0

Overall

8.0

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
3,174 reviews
Southwest
8.0
Very good
4,242 reviews

Entertainment

7.5

Crew

8.6

Boarding

8.1

Food

7.0

Comfort

8.0

Overall

8.0

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 St. Louis to Key Largo. 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 St. Louis to Key Largo?

    For a flight from St. Louis to Key Largo, you will be flying from Lambert-St Louis. Lambert-St Louis (STL) is just 12.7 mi from the center of the city. Lambert-St Louis is the only St. Louis airport and it handles 2 outbound flights to Key Largo per day. 6 airlines have flights to Key Largo from Lambert-St Louis on a regular basis.

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

    The Lambert-St Louis to Key Largo flight path was viewed by 56 users in the past month. Keep an eye out for changes in search interest prior to high and low season.

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

    For as low as $197, Delta can have you in Key Largo from St. Louis in 6h 14m. The distance between St. Louis and Key Largo is about 1069 mi.

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

    The top 3 most reliable airlines when flying from St. Louis to Key Largo are Envoy Air (100%), GOL (100%) and American Airlines (93%).

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

    On average you can expect to pay $760 for a flight from St. Louis to Key Largo. The cheapest flight overall is $139 while the most popular route, (Lambert-St Louis - Miami) is currently priced at $182.

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

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

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

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

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

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

    Currently, September is the cheapest month in which you can book a flight from St. Louis to Key Largo (average of $232). Flying from St. Louis to Key Largo in March is currently the most expensive (average of $289). 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

Browse thousands of different options on Cheapflights for your next trip

Toggle through the tabs below to find thousands of options on Cheapflights for your next trip.

Alternative routes for St. Louis to Key Largo

See prices for flight routes from nearby airports that may be better suited for you.
St. Louis to Orlando flights
Kansas City to Orlando flights
St. Louis to Miami flights
Kansas City to Miami flights
St. Louis to Fort Myers flights
Kansas City to Fort Lauderdale flights
St. Louis to Tampa flights
Kansas City to Tampa flights
St. Louis to Fort Lauderdale flights
St. Louis to Jacksonville flights
Springfield to Orlando flights
St. Louis to Key West flights
Kansas City to West Palm Beach flights
Springfield to Miami flights
Kansas City to Fort Myers flights
Kansas City to Jacksonville flights
St. Louis to Sarasota flights
Kansas City to Pensacola flights
St. Louis to Pensacola flights
Kansas City to Key West flights
St. Louis to West Palm Beach flights
Springfield to Pensacola flights
St. Louis to Panama City flights
Kansas City to Sarasota flights
Springfield to Tampa flights
Springfield to Fort Lauderdale flights
Kansas City to Panama City flights
Kansas City to Melbourne flights
Columbia to Pensacola flights
Kansas City to Daytona Beach flights
St. Louis to Valparaiso flights
Springfield to Valparaiso flights
Springfield to Key West flights
Kansas City to Valparaiso flights
Springfield to Panama City flights
Joplin to Pensacola flights
Springfield to Fort Myers flights
Columbia to Orlando flights
Springfield to Sarasota flights
St. Louis to Tallahassee flights
Springfield to Jacksonville flights
Springfield to West Palm Beach flights
Springfield to Melbourne flights
St. Louis to Daytona Beach flights
Kansas City to St Petersburg flights
St. Louis to Gainesville flights
Joplin to Miami flights
Columbia to Jacksonville flights
Kansas City to Tallahassee flights
Columbia to Tampa flights

Top 6 airlines flying from St. Louis to Key Largo

Discover the top 6 airlines that operate flights from St. Louis to Key Largo. 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 September 16, 2025.
AirlineCheapestAverageFlexibilityOn-time
Spirit AirlinesCheapest$68Average$155FlexibilityNo cancel feeOn-time65%
FrontierCheapest$143Average$230FlexibilityNo cancel feeOn-time62%
DeltaCheapest$196Average$416FlexibilityNo cancel feeOn-timeN/A
American AirlinesCheapest$243Average$425FlexibilityNo cancel feeOn-time71%
United AirlinesCheapest$245Average$489FlexibilityNo cancel feeOn-time69%
SouthwestCheapest$245Average$463FlexibilityNo cancel feeOn-time63%

100% Free

Cheapflights is completely free to use, so you can start saving the moment you arrive.

Book with Flexibility

Our users can plan ahead with confidence and find flights with no change fees

Travel Smart

Millions of people come to us for their flight needs every year. We help make travel planning easy by providing useful insights and data-driven graphs that can inform your decisions.