$440 Cheap Flights from St. Louis (STL) to Sofia (SOF)

View $440 flight on Fri, Feb 6, 2026Opens in a new window

Popular airlines from St. Louis Lambert Intl. Airport (STL) to Sofia Airport (SOF)

Cheap Flights from St. Louis to Sofia (STL-SOF)

Prices were available within the past 7 days and start at $440 for one-way flights and $532 for round trip, for the period specified. Prices and availability are subject to change. Additional terms apply.

United
Mon, Dec 8 - Wed, Dec 24
STL
St. Louis
SOF
Sofia
$532 Roundtrip, found 1 day ago
$532
Roundtrip
found 1 day ago
Select United flight, departing Mon, Dec 8 from St. Louis to Sofia, returning Wed, Dec 24, priced at $532 found 1 day ago
United
Wed, Nov 26 - Wed, Dec 10
STL
St. Louis
SOF
Sofia
$532 Roundtrip, found 3 days ago
$532
Roundtrip
found 3 days ago
Select United flight, departing Wed, Nov 26 from St. Louis to Sofia, returning Wed, Dec 10, priced at $532 found 3 days ago
United
Mon, Jan 12 - Sun, Jan 25
STL
St. Louis
SOF
Sofia
$534 Roundtrip, found 1 day ago
$534
Roundtrip
found 1 day ago
Select United flight, departing Mon, Jan 12 from St. Louis to Sofia, returning Sun, Jan 25, priced at $534 found 1 day ago
United
Tue, Jan 13 - Sun, Jan 25
STL
St. Louis
SOF
Sofia
$534 Roundtrip, found 2 days ago
$534
Roundtrip
found 2 days ago
Select United flight, departing Tue, Jan 13 from St. Louis to Sofia, returning Sun, Jan 25, priced at $534 found 2 days ago
United
Mon, Dec 8 - Thu, Dec 25
STL
St. Louis
SOF
Sofia
$539 Roundtrip, found 2 days ago
$539
Roundtrip
found 2 days ago
Select United flight, departing Mon, Dec 8 from St. Louis to Sofia, returning Thu, Dec 25, priced at $539 found 2 days ago
United
Mon, Jan 12 - Thu, Jan 22
STL
St. Louis
SOF
Sofia
$540 Roundtrip, found 1 day ago
$540
Roundtrip
found 1 day ago
Select United flight, departing Mon, Jan 12 from St. Louis to Sofia, returning Thu, Jan 22, priced at $540 found 1 day ago
British Airways
Sat, Dec 6 - Wed, Jan 14
STL
St. Louis
SOF
Sofia
$548 Roundtrip, found 4 days ago
$548
Roundtrip
found 4 days ago
Select British Airways flight, departing Sat, Dec 6 from St. Louis to Sofia, returning Wed, Jan 14, priced at $548 found 4 days ago
Air Canada
Sat, Dec 6 - Thu, Jan 15
STL
St. Louis
SOF
Sofia
$553 Roundtrip, found 4 days ago
$553
Roundtrip
found 4 days ago
Select Air Canada flight, departing Sat, Dec 6 from St. Louis to Sofia, returning Thu, Jan 15, priced at $553 found 4 days ago
KLM
Wed, Dec 10 - Wed, Dec 24
STL
St. Louis
SOF
Sofia
$601 Roundtrip, found 1 day ago
$601
Roundtrip
found 1 day ago
Select KLM flight, departing Wed, Dec 10 from St. Louis to Sofia, returning Wed, Dec 24, priced at $601 found 1 day ago
Air France
Tue, Dec 2 - Sat, Dec 13
STL
St. Louis
SOF
Sofia
$601 Roundtrip, found 3 days ago
$601
Roundtrip
found 3 days ago
Select Air France flight, departing Tue, Dec 2 from St. Louis to Sofia, returning Sat, Dec 13, priced at $601 found 3 days ago

Alternative airports near Sofia

Prices were available within the past 7 days. Prices and availability are subject to change.

Select flight to Sofia Airport SOF. Cheapest and Closest option available. Average driving time to city center is 11 minutes. Flights from $692
SOF
Sofia Airport
CheapestClosest
Average driving time to city center11 min
Flights from $692

Frequently asked questions

How much does a flight from Lambert-St. Louis Intl. Airport (STL) to Sofia Airport (SOF) cost?
Secure a cheap one-way flight from $440 or cheap return flight from $532 from Lambert-St. Louis Intl. Airport (STL) to Sofia Airport (SOF) with Expedia. Enter your travel dates and sort by "Price (lowest to highest)" to see our cheapest flight offers on this route.
What is the cheapest month to fly from Lambert-St. Louis Intl. Airport (STL) to Sofia Airport (SOF)?
Flying in December is a good way to save, as it's the cheapest month for flights between STL and SOF. You'll usually find the lowest prices during off-peak months.
What is the cheapest airline that flies from Lambert-St. Louis Intl. Airport (STL) to Sofia Airport (SOF)?
To find the cheapest airline flying from STL to SOF, use Expedia's filter tool. Tailor your search based on your travel needs, such as preferred carriers and flight duration. You can then sort your results by "Price (lowest to highest)" to see the cheapest fares upfront.
How many flights per day from Lambert-St. Louis Intl. Airport (STL) to Sofia Airport (SOF)?
Direct flights from Lambert-St. Louis Intl. Airport (STL) to Sofia Airport (SOF) aren't available daily, so you'll need to take a flight with a layover. Explore your options with our filter tool. Enter your travel dates and pick either "1 Stop" or "2+ Stops."
What day of the week has the most flights from STL to SOF?
Friday is generally the busiest day for flights, while Tuesday is often the quietest.* Remember that flight schedules can change based on a number of factors, including the time of year and airline.*Busiest/quietest day to travel is based on Expedia flight demand through January to December 2024.
What is the best time to fly from Lambert-St. Louis Intl. Airport (STL) to Sofia Airport (SOF)?
Choose a flight from Lambert-St. Louis Intl. Airport (STL) to Sofia Airport (SOF) that leaves before 3 PM to reduce the likelihood of delays. Departures after this hour are on average 22% more likely to be canceled.**Most reliable time of the day and month to travel recommendation is based on January through August 2024 flight status data sourced from OAG's global flight data platform.
Is it cheaper to buy a plane ticket from Lambert-St. Louis Intl. Airport (STL) to Sofia Airport (SOF) last-minute?
Last-minute bookings from STL to SOF are usually more expensive. To lock in the lowest prices, start searching for flights well ahead of time. That being said, if you can play around with your travel dates, it's possible to find a cheap fare right before your journey.
Is it cheaper to book a STL to SOF flight and hotel package?
Compared with arranging flights and hotels separately, booking a STL to SOF flight and hotel package with Expedia could result in significant savings. Better still, having everything in one place will take the stress out of planning your trip. Simply pick your flights and select from our wide range of stays, then personalize your trip with extras like car rentals and activities.
Can I cancel or change the date of my flight from Lambert-St. Louis Intl. Airport (STL) to Sofia Airport (SOF)?
If you booked your STL to SOF flight within the last 24 hours, you may be able to cancel or modify it without fees. Depending on the airline and the type of ticket you purchased, additional charges may apply for changes beyond that time. Airline policies and contact information can be found in your itinerary or confirmation email. Or, go to our Customer Service portal for further details.

Travel information

Origin airport
Lambert-St. Louis Intl.
Destination airport
Sofia
Airlines serving
Air Canada, Air France, Austrian Airlines, British Airways, KLM, Lufthansa, Turkish Airlines, United
Roundtrip price
$531
Distance
5448 mi

Book with confidence

St. Louis to Sofia Flights

The cheapest times to fly from St. Louis to Sofia

On average, Thursday can be the cheapest time to fly, according to data from the Airlines Reporting Corporation (ARC), one of the world's biggest databases for global airline sales. The data reveals that you could save up to 16% by flying on a Thursday—the cheapest day to travel on average—instead of a Sunday—the most expensive. Some of the most affordable flights from St. Louis to Sofia are during the month of December. You can find some of the cheapest flights from St. Louis to Sofia with Expedia's search tool and vast selection of airlines.

 

The best time to book a flight from St. Louis to Sofia

Sunday is one of the best days to book for cheap flights from St. Louis to Sofia: Tickets reserved on a Sunday cost between 6% and 13% less than those reserved on a Friday, according to ARC data. The data also suggests booking early can also lead to cheaper airfares. You could save 24% by buying your tickets for domestic flights at least a month in advance and 10% by booking international flights 2 months in advance.

 

How to find cheap round-trip tickets from St. Louis to Sofia

Being flexible with your dates and using Expedia's Price Drop Protection and Price Tracking features are some of the best ways of finding a cheap ticket from St. Louis to Sofia in 2025. You can also book with separate airlines for your outbound and return journeys, from $440 one-way. Expedia also offers Price Drop Protection, so if the cost of your airfare goes down after booking, you'll receive a credit for the difference*. This is available for a small fee, and is free to One Key Gold and Platinum tier members.

 

Expedia's Price Tracking feature means you can stay on top of airfares without manually checking every day. It sends you automated price alerts for cheap St. Louis to Sofia flights and uses historical data to indicate when the best time to book is. Download Expedia's free app to activate this handy tool in a few easy taps.

 

You could also save big by booking one of Expedia's vacation packages. Bundling together your St. Louis to Sofia airfare with your accommodations and car rental is often cheaper than booking everything separately. There’s also One Key, Expedia's generous rewards program. Join for free and you could earn One Key cash on most bookings to save on future adventures.

 

*Terms apply.

 

Disclaimer: ARC The statistics are based on average round-trip ticket prices between January and August 2023. The percentages you see are averages.

 

St. Louis to Sofia Flights

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*Available to One Key members.