Cheap flights from San Francisco to Ontario from $20 SFO → ONT

Found recently, and the cheapest we hold

What have prices looked like?

Over 49 days, 24 Sept to 11 Nov, the cheapest return we saw each day was $34 to $109.

At $220, the cheapest return found recently is above that range.

Those were the prices on those days, not today's.

Could nearby dates be cheaper?

We hold no other 1-night return fares leaving within 3 days of 21 Nov to compare.

Every date we hold

85 fares on 6 departure dates

Which month looks cheapest?

December 2026 is the cheapest month — from $47.

Found recently, and the cheapest we hold

What have prices looked like?

Over 49 days, 24 Sept to 11 Nov, the cheapest one-way we saw each day was $17 to $75.

Those were the prices on those days, not today's.

Could nearby dates be cheaper?

No. We hold one-way fares on 1 other departure date within 3 days of 8 Dec, and it is not cheaper.

Every date we hold

9 fares on 9 departure dates

Which month looks cheapest?

December 2026 is the cheapest month — from $19.

Return

Fares 30 to 59 days before departure were typically 68% lower than 0 to 6 days before departure.

From the cheapest return each day between 24 Sept and 11 Nov (49 days), grouped by how many days ahead the flight left; one adult in economy.

Each range covers different departure dates, so this compares typical fares, not the same trip priced twice.

Prices reflect recent searches — current fares may differ.

One-way

Fares 30 to 59 days before departure were typically 60% lower than 0 to 6 days before departure.

From the cheapest one-way each day between 24 Sept and 11 Nov (49 days), grouped by how many days ahead the flight left; one adult in economy.

Each range covers different departure dates, so this compares typical fares, not the same trip priced twice.

Prices reflect recent searches — current fares may differ.

How much is a return flight from San Francisco to Ontario?

The cheapest return found recently is $220 with Frontier Airlines, 21 Nov to 22 Nov, found yesterday. The cheapest return we hold, of any age, is $47 with Frontier Airlines, 14 Dec to 18 Dec, found 8 days ago. The cheapest return fare on each of 6 departure dates is usually $79 to $212.

How much is a one-way flight from San Francisco to Ontario?

The cheapest one-way found recently is $20 with Frontier Airlines, 8 Dec, found 2 days ago. The cheapest one-way we hold, of any age, is $19 with Frontier Airlines, 16 Dec, found 6 days ago. The cheapest one-way fare on each of 9 departure dates is usually $20 to $111.

What is the cheapest month to fly from San Francisco to Ontario?

December 2026 is the cheapest month for a return, from $47, 14 Dec to 18 Dec, found 8 days ago. It is the cheapest month for a one-way too, from $19, 16 Dec, found 6 days ago.

How far ahead should I book a flight from San Francisco to Ontario?

In 49 days of prices between 24 Sept and 11 Nov, return fares 30 to 59 days before departure were typically 68% lower than 0 to 6 days before departure. One-way fares 30 to 59 days before departure were typically 60% lower than 0 to 6 days before departure.

Is there a direct flight from San Francisco to Ontario?

Yes, the cheapest nonstop return found recently is $220 with Frontier Airlines, 21 Nov to 22 Nov, found yesterday. The cheapest nonstop one-way found recently is $20 with Frontier Airlines, 8 Dec, found 2 days ago.

How long is the flight from San Francisco to Ontario?

The cheapest nonstop one-way found recently, with Frontier Airlines on 8 Dec, takes 1 h 27 min from San Francisco International Airport (SFO) to Ontario International Airport (ONT).

Which airlines have the cheapest flights from San Francisco to Ontario?

Between 16 Nov and 24 Dec, Frontier Airlines has the cheapest return on 5 of the 6 departure dates we hold, and United Airlines on 1. Between 13 Nov and 16 Dec, Frontier Airlines has the cheapest one-way on all 9 departure dates we hold.