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Cheap flights Ontario — St Louis

Ontario (ONT, US) St Louis (STL, US)
from $84 2 500 km ~3h 26m 4 flights found 1 airlines cheapest on Thursday
Reverse route
How many travellers?
Adults
12+ years
1
Children
2–11 years
0
Infants
under 2
0
Choose your departure date
Cheapest: $84 on 04.12.2026
Prices shown are from searches by other travellers over the last 24 hours. Missing a date? Click any day — we'll find tickets anyway.
November 2026
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December 2026
Mo
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January 2027
Mo
Tu
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Prices found for 2 of 90 days. Prices update as more travellers search. Click any date to search live.
Depart
—
Return
—
Cheapest flights found
04 Dec 2026, Fri
Frontier Airlines F9 1500
17:00
ONT Ontario International Airport
21:31
STL Lambert-St. Louis International Airport
4h 31m 1 stop
Mytrip.com
$84
View this ticket
14 Jan 2027, Thu
Frontier Airlines F9 4758
05:27
ONT Ontario International Airport
09:50
STL Lambert-St. Louis International Airport
4h 23m 1 stop
Trip.com
$144
View this ticket
Route characteristics
Distance
2 500 km
Flight time
3h 26m
Time difference
+2h
Minimum price
from $84 (04.12.2026)
Average price
$114
Maximum price
$144
Cheapest day
Thursday
Departure airports (1)
ONT Ontario International Airport
Arrival airports (1)
STL Lambert-St. Louis International Airport
Airlines (1)
F9 Frontier Airlines
Agencies (3)
Mytrip.com Trip.com Farera
Prices by day of week
Thursday
$144
avg $144
Cheapest
Friday
$84
avg $84
Price trend by month
December 2026
from $84
avg $84
1 flights
January 2027
from $144
avg $144
1 flights
Airlines — cheapest prices 1
Frontier Airlines
Frontier Airlines
Low-cost 4 flights · 4 days
$84
Where to buy tickets 3
Mytrip.com
1 tickets · 1 days
from $84
Trip.com
1 tickets · 1 days
from $144
Farera
2 tickets · 2 days
from $171
Airports

From — Ontario (1)

  • ONT Ontario International Airport

To — St Louis (1)

  • STL Lambert-St. Louis International Airport
Other destinations from Ontario
Albuquerque
US
Accra
GH
Nantucket
US
Adelaide
AU
San Andres Island
CO
Malaga
ES · Hub
Auckland
NZ
Almaty
KZ
Alicante
ES
Ahmedabad
IN
Amsterdam
NL · Hub
Anchorage
US
Frequently asked questions about the route Ontario — St Louis
How long is the flight from Ontario to St Louis?
Approximate flight time — 3h 26m. This is an average for a direct flight. With connections, the time may be longer.
What is the distance from Ontario to St Louis?
The straight-line distance — 2 500 km.
How much do flights from Ontario to St Louis cost?
The minimum price over 3 months — from $84 on 04.12.2026.
What is the average ticket price?
The average price — $114. Range: $84 — $144.
What is the time difference between Ontario and St Louis?
The difference — +2h.
From which airports does Ontario operate flights?
From Ontario: ONT (Ontario International Airport).
To which airports in St Louis do flights arrive?
To St Louis: STL (Lambert-St. Louis International Airport).
Which airlines fly this route?
This route is served by 1 airline: Frontier Airlines.
Which day of the week is cheapest?
The cheapest day of the week — Thursday.
When is the best time to buy tickets?
Optimal — 1–3 months before departure. Check the calendar above — it shows the best dates.
How do I book flights?
Click "View this ticket" on any flight card — you'll be redirected to the booking page with this specific ticket pre-selected.
About the route Ontario — St Louis

Flights Ontario — St Louis is a popular route. The straight-line distance is 2 500 km. Flight time 3h 26m. Time difference +2h.

From Ontario (ONT) flights depart from 1 airport: ONT. To St Louis (STL) — 1 arrival airport: STL.

1 airline operate on this route: Frontier Airlines.

The minimum price for the next 3 months — from $84 (04.12.2026). The cheapest dates are highlighted in the calendar above.

The average ticket price — $114, ranging from $84 to $144. Book 1–3 months in advance to get the best deals.

Cheapest day to fly — Thursday.

Other destinations in United States from Ontario
Philadelphia
US
Oklahoma City
US
Omaha
US
Orlando
US
Everett
US
West Palm Beach
US
Portland
US
Palm Springs
US

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