Cheap flights from St Louis to Ontario

One-way fares from $66 · STL → ONT · prices found by travellers in the last 48 hours

Compare all dates Ontario → St Louis
Cheapest fare
$66

Frontier Airlines · Wed, Jan 27

Cheapest month
January

from $66

Direct flights
Not recently

Usually 1+ stop

Quickest trip
4h 53m

2,500 km

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Cheapest month to fly from St Louis to Ontario

Lowest one-way fare per person in each month. Choose a month to see every date.

  1. November 2026 $175
  2. January 2027 Cheapest $66

Plan the rest of your trip to Ontario

Where to stay, what to do and getting around, from our travel partners.

Where to stay

Hotels in OntarioCompare places to stay on Booking.com Find hotels →

Things to do

Things to do in OntarioTours, attractions and day trips on Klook Explore →

Getting around

Airport transfer in OntarioPre-book a driver to meet you at arrivals, with Kiwitaxi Book a transfer → Car hire in OntarioCompare rental cars from major brands on EconomyBookings Compare cars →

About flights from St Louis to Ontario

St Louis (STL) and Ontario (ONT) are about 2,500 km apart. We haven't seen direct fares on this route recently, so expect at least one stop; the quickest journey we've seen takes about 4h 53m. Over the next few months, one-way fares start from $66, and January 2027 is currently the cheapest month to fly.

These prices come from searches travellers made in the last 48 hours, so they move quickly. If you see a good fare, it's worth booking soon. FlightsExp is free to use: you book directly with our travel partner.

Frequently asked questions

How much is a flight from St Louis to Ontario?

The cheapest one-way fare we've seen recently is $66 with Frontier Airlines, departing Wednesday, January 27, 2027. Over the coming months, the lowest fare in each month ranges from $66 to $175.

What is the cheapest month to fly from St Louis to Ontario?

January 2027 currently has the lowest fares, from $66 one way.

Are there direct flights from St Louis to Ontario?

We haven't seen direct fares recently, so most journeys include at least one stop.

How long is the flight from St Louis to Ontario?

The quickest journey we've seen takes about 4h 53m. St Louis and Ontario are around 2,500 km apart.

Which airlines fly from St Louis to Ontario?

Recent fares on this route were with Frontier Airlines.

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