$82 Find Cheap Flights from Boston to St. Charles

This is the cheapest one-way flight price found by a KAYAK user in the last 72 hours by searching for a flight from Boston to St. Charles departing on 6/3. Fares are subject to change and may not be available on all flights or dates of travel. Click the price to replicate the search for this deal.
1 adult
1 adult, Economy, 0 bags

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Everything you should know

Cheapest round-trip
$346
Typical prices: $594-$384
Frontier
Sat 6/13Mon 6/15
BOS - STL • 2 stops
Cheapest non-stop
$353
Typical prices: $607-$418
Southwest
Thu 5/28Sat 5/30
BOS - STL • Non-stop
Arrival airport
You can't fly directly to St. Charles. It is served by St. Louis (STL), located 7.2 miles from St. Charles.
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Flight Deals
Useful Info
Flight Deals

Cheap Flights from Boston to St. Charles (BOS-STL)

 
Here are some of the best deals found on KAYAK recently from the most popular airlines for round-trip flights from Boston to St. Charles that are departing in the next months. While these flights were available on KAYAK in the last 72 hours, prices and availability are subject to change and deals may expire.
Discover the best prices for you by selecting your travel dates on KAYAK.

Recent round-trip flight deals from Boston to St. Charles

Sat, Jun 13 - Mon, Jun 15
Frontier Logo
12:01 pm - 11:49 pm
BOS
-
STL
12h 48m
2 stops
Frontier Logo
5:06 pm - 7:52 am
STL
-
BOS
13h 46m
1 stop
$346Frontier
Tue, Jun 2 - Mon, Jun 8
Frontier Logo
9:12 am - 5:33 pm
BOS
-
STL
9h 21m
1 stop
Frontier Logo
8:08 pm - 1:27 am
STL
-
BOS
28h 19m
2 stops
$347Frontier
Fri, May 29 - Tue, Jun 2
Frontier Logo
6:00 am - 8:11 pm
BOS
-
STL
15h 11m
2 stops
Frontier Logo
6:33 pm - 7:49 am
STL
-
BOS
12h 16m
1 stop
$348Frontier
Wed, Jul 8 - Sun, Jul 12
Frontier Logo
11:05 am - 5:37 pm
BOS
-
STL
31h 32m
2 stops
Frontier Logo
6:33 pm - 7:46 am
STL
-
BOS
12h 13m
1 stop
$350Frontier
Wed, Jun 3 - Wed, Jun 10
Southwest Logo
2:25 pm - 10:00 pm
BOS
-
STL
8h 35m
2 stops
Southwest Logo
7:10 pm - 10:40 pm
STL
-
BOS
2h 30mnonstop
$352Southwest
Thu, May 28 - Mon, Jun 1
Southwest Logo
6:45 pm - 8:55 pm
BOS
-
STL
3h 10mnonstop
Southwest Logo
7:40 pm - 11:10 pm
STL
-
BOS
2h 30mnonstop
$353Southwest
Thu, May 28 - Fri, May 29
Frontier Logo
9:12 am - 5:33 pm
BOS
-
STL
9h 21m
1 stop
Frontier Logo
5:27 pm - 7:49 am
STL
-
BOS
13h 22m
1 stop
$354Frontier
Thu, Jun 4 - Tue, Jun 9
Southwest Logo
5:35 am - 7:25 am
BOS
-
STL
2h 50mnonstop
Southwest Logo
11:20 am - 6:00 pm
STL
-
BOS
5h 40m
1 stop
$355Southwest
Mon, Jun 1 - Thu, Jun 11
Frontier Logo
12:01 pm - 7:23 pm
BOS
-
STL
32h 22m
2 stops
Frontier Logo
6:31 pm - 1:27 am
STL
-
BOS
29h 56m
1 stop
$356Frontier
Wed, May 27 - Tue, Jun 9
Delta Logo
4:30 pm - 9:38 pm
BOS
-
STL
6h 08m
1 stop
Delta Logo
6:05 am - 12:22 pm
STL
-
BOS
5h 17m
1 stop
$357Delta
Useful Info

Good to know

Low seasonJanuary
Cheapest flight$82
Best time to beat the crowds with an average 14% drop in price.
Most popular time to fly with an average 3% increase in price.
Flight from Boston to St. Louis

When to book flights from Boston to St. Charles

Are your dates flexible? Find out the best times to travel from Boston to St. Charles based on our flight data from the last year. Discover the cheapest month and even day to fly.
Estimated round-trip price

FAQs for booking flights from Boston to St. Charles

  • Which airports will I be using when flying from Boston to St. Charles?

    When flying out of Boston you’ll be using Boston Logan Intl. St. Charles does not have its own airport so you’ll be flying into nearby Lambert-St Louis airport, which is 7.2 mi away.

  • How long does a flight from Boston to St. Charles take?

    Direct flights cover the 1,043 miles separating Boston and St. Charles in about 2h 50m.

  • How many flights are there between Boston and St. Charles?

    13 direct flights run between Boston and St. Charles on a daily basis. On average, there are about 96 departures each week.

  • What’s the cheapest day of the week to fly between Boston and St. Charles?

    Consider leaving on a Friday and avoid Saturdays if you are looking for the best rates. For your return to Boston, you’ll find the best rates on Wednesdays and the most expensive ones on Saturdays.

  • How does KAYAK find such low prices on flights from Boston to St. Charles?

    KAYAK is a travel search engine. That means we look across the web to find the best prices we can find for our users. With over 2 billion flight queries processed yearly, we are able to display a variety of prices and options on flights from Boston to St. Charles.

  • How does KAYAK's flight Price Forecast tool help me choose the right time to buy my flight ticket from Boston to St. Charles?

    KAYAK’s flight Price Forecast tool uses historical data to determine whether the price for a flight to St. Charles from Boston is likely to change within 7 days, so travelers know whether to wait or book now.

  • What is the Hacker Fare option on flights from Boston to St. Charles?

    Hacker Fares allow you to combine one-way tickets in order to save you money over a traditional round-trip ticket. You could then fly to St. Charles with an airline and back to Boston with another airline.

  • What is KAYAK's "flexible dates" feature and why should I care when looking for a flight from Boston to St. Charles?

    Sometimes travel dates aren't set in stone. If your preferred travel dates have some wiggle room, flexible dates will show you all the options when flying to St. Charles from Boston up to 3 days before/after your preferred dates. You can then pick the flights that suit you best.

  • Which airlines provide the cheapest flights from Boston to St. Charles?

    In the last 72 hours, the cheapest one-way ticket between Boston and St. Charles found on KAYAK was with Frontier for $67. Spirit Airlines offered a round-trip connection from $63 and Frontier from $90.

Top tips for finding cheap flights from Boston to St. Charles

  • There is no airport in St. Charles. Instead, you’ll be flying into St. Louis Lambert Airport when flying between Boston and St. Charles.
  • The cheapest flight from Boston to St. Charles was found 51 days before departure, on average.
  • Book at least 3 weeks before departure in order to get a below-average price.
  • High season is considered to be June, July and August. The cheapest month to fly is August.

Reviews of the top 5 airlines serving Boston to St. Charles

 
Need help choosing which airline to fly with from Boston to St. Charles? KAYAK airline reviews give an overall score for each airline based on loads of factors, including comfort, boarding, in-flight entertainment and more, to make your decision easier. See airline scores according to verified KAYAK customer reviews.
7.9
SouthwestOverall score based on 4300 reviews
8.1Boarding
7.0Food
7.5Entertainment
8.6Crew
8.0Comfort
Airline reviews

I'm glad it wasn't only 75% full because I could get a good seat

8.0 ExcellentBobby, May 2026
BNA - GSP
Read more Southwest reviews

I'm glad it wasn't only 75% full because I could get a good seat

if I was good. Not happy that I have to pay extra money to get the seat I need for lake room, but I guess that’s a sign of the times.

Seats were very comfortable. They tilted back. Drinks and snacks were free and served 3 times. Attendants were awesome.

Plane was clean and comfortable. Flight attendants and gate staff were professional, friendly and efficient. Boarding and deplaning were orderly and efficient. All in all, the typical excellent Southwest experience.

Truly terrible. Will never willingly fly southwest again. Seats are worse than before they switched to assigned seating. One flight attendant was the opposite of helpful (rude, unhelpful, dismissive, and as my stranger seatmate said unprompted: a total prick). This caused me, 15 minutes into the flight, to book an alternate return flight home on a competing airline (first class 1.2k purchase instead of my existing planned flight) just so I would not have to ever be on that aircraft, with that terrible service person, with those horrific seats ever again.

Not having a five hour delay with little notice! The crew was very kind, though, and just as tired as we passengers were. The flight didn't depart until nearly 1 am...and no reason was ever given.

The entire experience from boarding to landing was amazing! The crew were very friendly. Will definitely be back.

no service at all due to turbulence. they should've at least given us snacks, there were only 10 people on the entire flight.

First time I've had to use the disabled accommodations. And I could not have had a better experience with Southwest, i was having trouble getting from one terminal to another due to my heart failure. And the next thing I know a Southwest agent had made sure. I had a wheelchair at all my flights. Can't thank them enough.

Delayed flight, lack of information, boarding process is a mess as is the carryon luggage causing issues when leaving the plane….just a poor experience.

It was a pleasant surprise to have complimentary Wi-Fi on the flight

Much better than Latam, the worse airline company ever. I hope I don't have the need to fly Latam ever in my life again.

Seats in Delta Main are unbelievably close to the seat in front of. Hard to get a backpack under the seat.

The agent at check in and at the gate were less than thrilled to be at work. I'm not a fan of Kayak's placement on the plane. I got put in the middle seat and none of my preferences were used.

In ATL they have two sets of departure screens. Follow what is on your airline's departure board - the ATL Airport Authority departure board had completely incorrect details about the gate assignment for my flight, which would have made me miss boarding.

Flight was delayed it was hot while sitting on the plane, one engine was working on the plane until they had to do some jimmy rigging down the runway in order for the other engine to charge up. It was ridiculous

The flight was very good and the staff was very friendly and helpful!

The only thing I would say is we tried to get on a standby earlier flight, but with our fair we couldn’t. That seems senseless to leave with open seats..

Very easy to use and convenient, you can perform any action within the same portal

In a world of delays, Delta was on time both ways! Boarding was fast and efficient. Staff was friendly. AND wifi worked.

The space between seat rows seemed to be larger than other airlines. I didn’t check their food or entertainment since I slept most of the way. They do seem to have a lot of options for purchase though.

Kayak sucked. You gave me a confirmation number that was not useable by the jet blue system. Nor did you send any check in emails. I’ll not be using your site again. Nice work.

Given us a free miles or free flight for waiting for 9 hours I didn’t get home till 5am in the morning and I was supposed to be home at 9:30 touch down.

Excellent price. Everything on time. two bad parts. Kayak said I couldn't sign in for the flight online, but I got an email at the same time from Jet Blue and they let me sign in online. Second bad part was that, although I had provided my known traveler number, neither of my boarding passes, for this flight and the previous one, had TSA pre-check showing.

Jet blue was great But the Jayak system Wasa pure nightmare and wasted so much of my time and energy by not giving me a way to access jet blue to check in the flight back I didn’t even get the number confirmation code 24 hours before. Because I didn’t receive the email with the confirmation code I could NoT CHECk IN. I spoke to a kayak third party and they informed me I could not carry a carry on, on the flight which caused me so much extra stress it was just too much. You can be sure I will not be using it recommending your site. Again.

There was a screen but no earphones that could use the older input so I could listen to anything.

My experience with JetBlue was fine BUT I am very upset with Kayak! JetBlue had delayed our scheduled departure by an hour and you NEVER notified me of the change. I did not hear directly from JetBlue because the trip was booked through Kayak, a mistake I will not repeat. Your reminder of the our trip last week still had the WRONG departure time. Our return trip has also changed, and again no notice from you.

Jet blue just had great service overall! Only a little turbulence heading out of Austin, otherwise the jet stream helped the speed of the trip!

Boarding was quick and efficient. The flight crew were friendly. There were limited food options available on the flight. The pocket guide said there would be salad and sandwich sections available on flights over 3.5 hours. The only food available were snack boxes. And those were limited as well. My flight was over 5 hours. The entertainment system worked well. I had both extra legroom seats and regular coach seats. The seats were not very comfortable. The entertainment controls in the armrest made it difficult to rest my arm without changing the channel on my neighbors TV. Overall, my experience was mediocre.

Purchased through 3rd party vendor which made everything difficult. Unable to check in online. Unable to get flight updates easily, tsa precheck information didn’t carry through, longer time to check in in person. Entertainment looked good but had to purchase conventional headphones to view.

We had several flights and they were all on-time and flawless

My Frequent Flyer nber wasn't put on as I was told it was..... This resulted in a last group boarding and no priority tags on My bags.

Terrible steward... Plane was quite empty... I asked to move "back" in the plane and the steward said no... Unnecessary power trip of mediocre people.

The small flights with Valet Luggage has a poor service

not sure why you ask about food, I n3ver get food on flights except maybe cookies or pretzels. wifi was slow and in and out most of the flight not good.

Cancelled BOYH legs of our flight home 30 min before initial boarding

Cancelled the flight half hour before boarding. Then cancelled the connecting flight too.

Left early arrived early..right amount of talking from pilots..of course had to love the biscuit and water!

I would like a refund for the extra cost the seat I paid for. An oversized person sat next to me and I couldn’t fit on my seat and had to move to another seat.

Boarding gate at LAX was too crowded—two gates next to one another

The staff at the check in counter was so rude. Made you feel Incompetent

Frontier scheduled a 40 minute connection in DEN. What they failed to mention was that they “close the doors” 20 mins prior to departure, which means you only have 20 mins. Not enough time. Possibly against DOT regulations. Filing complaint.

Flight was scheduled at 9:40pm. Got delayed to 10 am, the next day. crazy

The bag check, flight check-in, and onboard experience convinced my wife and me that we will actively go out of our way to avoid flying Frontier Airlines in the future. At bag check, we were informed that check-in could only be completed via the Frontier mobile app. Unfortunately, the app was extremely frustrating—sending us through repetitive, confusing loops that repeatedly forced us to decline add-on services with nearly every click. While most airline apps upsell, this one felt intentionally exhausting. As the process dragged on, we became genuinely concerned that my phone battery would die before check-in could be completed. We approached the bag check staff—who were standing together talking—and explained both our frustration and our predicament. They laughed. Later, my wife described the interaction as “gaslighting,” which felt accurate. We were then informed it would cost $25 per person simply to have our boarding passes printed. From that point forward, the tone of the experience was consistently hostile. The bag check employees were condescending and combative, behaving more like bullies than customer service staff. Unfortunately, that same attitude continued onboard. One flight attendant argued with me when I attempted to stow my backpack in the overhead bin. I explained that we had each paid $75 to check our bags specifically so we would not need to use carry-on space and could have adequate legroom. She demanded to see my ticket, pointed out that it said “no carry-on”—which I acknowledged—and I reiterated that this was precisely why we paid to check our bags. Her response was, “I don’t make the rules.” She then walked away, but not before asking if I “truly wanted to fly back to Chicago today?”—an unnecessary and unmistakable threat. It is also worth noting that despite booking our tickets together in the same transaction, we were not seated together. Upon our return to Chicago—where we could once again sit together—we compared onboard experiences. We both remarked on how unhappy the flight attendants appeared and how each of us was separately asked whether we would like to purchase a beverage. We declined. At no point was water mentioned as an option, leaving us with the clear impression that even water came at a cost—or that complimentary water, if available at all, was deliberately left unmentioned. Overall, the experience was shocking and deeply disappointing, but it was also a profound learning experience—one we will not forget and will not repeat. -Steve

Plane was hot and miserable and the crew was rude!

12 hour delay required getting on and off plane 3 times - would have at least liked to have been offered a snack or drink

They didn’t offer a water, even after I asked

They switched our terminal 3 times and we were delayed for four plus hours!!!

It was an early flight and most people napped/slept and the crew let us which was nice.

The crew acted like they had never done this and kept barking passive aggressive orders at people. + the security line + the delay + sitting on the tarmac for 2 hours + none of the apps or signage updating with correct times

Everything you need to know for your flight from Boston to St. Charles

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