$124 Cheap United flights Kalispell (FCA) to St. Louis (STL)

Landing cheap one-way United Airlines flights from FCA to STL from $124 on Expedia couldn't be easier — just filter by "Price (lowest to highest)." Alternatively, check out our budget-friendly return fares from $327 for your next exciting getaway.**These prices were available on Expedia within the past 7 days, for flights departing within the next year. Prices and availability are subject to change. Additional terms apply.

To find cheap United Airlines fares from Glacier Park Intl. Airport (FCA) to Lambert-St. Louis Intl. Airport (STL), start searching one to three months before your intended departure. Reserving domestic flights 34 to 86 days in advance could save you 25% compared to booking just 6 to 12 days ahead. The day you book can also impact what you pay. Sunday is typically the cheapest, while Monday is often the most expensive for domestic flights. You can save 6% on average by booking your journey on a Sunday.**Ideal booking window recommendation is based on average round-trip ticket prices for January through November for 2024. Best day of the week to book recommendation is based on average round-trip ticket prices for January through October 2024. All data sourced from ARC's global airline sales database.

Browse United Airlines's earliest flights from FCA to STL by using the "Morning" and "Early Morning" filters. Not only will you arrive sooner, early departures are also 20% less likely to be canceled.**Most reliable time of the day recommendation is based on January through August 2024 flight status data sourced from OAG's global flight data platform.

Depart from FCA to STL with United Airlines and you can look forward to a range of perks including a rewarding loyalty program. When booking through Expedia as a United Mileage Plus and One Key™ member, you can also earn OneKeyCash™* to spend on select future travel purchases.*OneKeyCash™ disclaimer - OneKeyCash™ is not redeemable for cash and can only be used on Expedia, Hotels.com and Vrbo.