Ontario to Denver ONT → DEN
Ontario International Airport (ONT) → Denver International Airport (DEN)
The cheapest return found recently is $218 with Frontier Airlines, 4 Nov – 11 Nov, found yesterday. The cheapest one-way found recently is $141 with Frontier Airlines, 28 Oct, found yesterday.
Return
The cheapest return fare on each of 4 departure dates is usually $195 to $308.
Cheapest return found recently
$218
4 Nov – 11 Nov · Frontier Airlines
Ontario International Airport (ONT) → Denver International Airport (DEN)
Leaves 5:07 p.m. · Return leaves 10:40 a.m. · 12 h 40 min of travel, both ways together
out 1 stop, back 1 stop
found yesterday
Cheapest nonstop return
$305
12 Nov – 19 Nov · Frontier Airlines
Ontario International Airport (ONT) → Denver International Airport (DEN)
Leaves 6:30 a.m. · Return leaves 10:55 p.m. · 4 h 49 min of travel, both ways together
out nonstop, back nonstop
found yesterday
Found recently, and the cheapest we hold
$218 4 Nov – 11 Novfound yesterdaySee prices for these dates
$125 9 Jan 2027 – 14 Jan 2027found 5 days agoSee prices for these dates
What have prices looked like?
Over 25 days, 24 Sept to 18 Oct, the cheapest return we saw each day was $92 to $347.
25 days is a short history, so treat this range as an early guide.
Those were the prices on those days, not today's.
Is this a good return price?
Compared with the cheapest return fare on each of 4 departure dates from 4 Nov to 9 Jan 2027, found by travelers' searches in the last 7 days (economy, the price the seller showed on Aviasales). The usual range is the middle half of those prices.
Could nearby dates be cheaper?
We hold no other 7-night return fares leaving within 3 days of 4 Nov to compare.
Every date we hold
4 fares on 4 departure dates
See the chart as a table
| Dates | From | Airline | Airports | Stops | Found | |
|---|---|---|---|---|---|---|
| 4 Nov – 11 Nov | $218 | Frontier Airlines | Ontario International Airport (ONT) → Denver International Airport (DEN) | out 1 stop, back 1 stop | found yesterday | See prices for these dates |
| 12 Nov – 19 Nov | $305 | Frontier Airlines | Ontario International Airport (ONT) → Denver International Airport (DEN) | out nonstop, back nonstop | found yesterday | See prices for these dates |
| 24 Dec – 28 Dec | $315 | Frontier Airlines | Ontario International Airport (ONT) → Denver International Airport (DEN) | out 1 stop, back nonstop | found today | See prices for these dates |
| 9 Jan 2027 – 14 Jan 2027 | $125 | United Airlines | Ontario International Airport (ONT) → Denver International Airport (DEN) | out nonstop, back nonstop | found 5 days ago | See prices for these dates |
Which month looks cheapest?
January 2027 is the cheapest month — from $125.
Airlines on the cheapest dates: Frontier Airlines, United Airlines.
One-way
The cheapest one-way fare on each of 4 departure dates is usually $52 to $95.
Cheapest one-way found recently
$141
28 Oct · Frontier Airlines
Ontario International Airport (ONT) → Denver International Airport (DEN)
Leaves 5:07 p.m. · 5 h 42 min trip
1 stop
found yesterday
Cheapest nonstop one-way
$79
22 Nov · Frontier Airlines
Ontario International Airport (ONT) → Denver International Airport (DEN)
Leaves 6:45 a.m. · 2 h 21 min trip
nonstop
found 2 days ago
Found recently, and the cheapest we hold
$141 28 Octfound yesterdayOpen this trip
$38 12 Novfound 4 days agoOpen this trip
What have prices looked like?
Over 25 days, 24 Sept to 18 Oct, the cheapest one-way we saw each day was $29 to $81.
At $141, the cheapest one-way found recently is above that range.
25 days is a short history, so treat this range as an early guide.
Those were the prices on those days, not today's.
Is this a good one-way price?
Compared with the cheapest one-way fare on each of 4 departure dates from 28 Oct to 10 Dec, found by travelers' searches in the last 7 days (economy, the price the seller showed on Aviasales). The usual range is the middle half of those prices.
Could nearby dates be cheaper?
We hold no other one-way fares leaving within 3 days of 28 Oct to compare.
Every date we hold
4 fares on 4 departure dates
See the chart as a table
| Dates | From | Airline | Airports | Stops | Found | |
|---|---|---|---|---|---|---|
| 28 Oct | $141 | Frontier Airlines | Ontario International Airport (ONT) → Denver International Airport (DEN) | 1 stop | found yesterday | Open this trip |
| 12 Nov | $38 | Frontier Airlines | Ontario International Airport (ONT) → Denver International Airport (DEN) | nonstop | found 4 days ago | Open this trip |
| 22 Nov | $79 | Frontier Airlines | Ontario International Airport (ONT) → Denver International Airport (DEN) | nonstop | found 2 days ago | Open this trip |
| 10 Dec | $56 | Frontier Airlines | Ontario International Airport (ONT) → Denver International Airport (DEN) | nonstop | found 4 days ago | Open this trip |
Which month looks cheapest?
November 2026 is the cheapest month — from $38.
Airlines on the cheapest dates: Frontier Airlines.
Premium cabin fares from Ontario to Denver
We hold no premium economy, business or first-class fares for this route: we collect them for the busiest routes, and this one is not among them yet.
Today's prices for 4 Nov – 11 Nov in another cabin: Premium economy · Business · First
Today's prices for 28 Oct in another cabin: Premium economy · Business · First
How far ahead were prices cheapest for Ontario to Denver?
Return
Fares 30 to 59 days before departure were typically 74% lower than 0 to 6 days before departure.
From the cheapest return each day between 24 Sept and 18 Oct (25 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.
See these ranges as a table
| Booked ahead by | Typical fare | Cheapest day | Above the cheapest | Days of prices |
|---|---|---|---|---|
| 0–6 days | $347 | $257 | +277% | 15 |
| 7–13 days | $260 | $97 | +182% | 16 |
| 14–29 days | $298 | $97 | +224% | 14 |
| 30–59 days | $92 | $92 | Cheapest seen | 8 |
One-way
The cheapest fares were 14 to 29 days before departure.
From the cheapest one-way each day between 24 Sept and 18 Oct (25 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.
See these ranges as a table
| Booked ahead by | Typical fare | Cheapest day | Above the cheapest | Days of prices |
|---|---|---|---|---|
| 14–29 days | $29 | $29 | Cheapest seen | 9 |
| 30–59 days | $38 | $29 | +31% | 25 |
| 60–89 days | $37 | $35 | +28% | 19 |
Could a nearby airport be cheaper?
A different airport at either end can change the fare — sometimes a lot.
Return
Los Angeles → Denver
56 km from Ontario
$171
$47 less than flying from Ontario
12 Nov – 19 Nov · LAX → DEN · out nonstop, back nonstop
found yesterday
Long Beach → Denver
60 km from Ontario
$264
$46 more than flying from Ontario
12 Nov – 19 Nov · LGB → DEN · out nonstop, back nonstop
found yesterday
Ontario → Vail
119 km from Denver
$576
$358 more than flying to Denver
28 Oct – 28 Oct · ONT → EGE · out 1 stop, back 1 stop
found yesterday
Cheapest recent price on each route — round trip, per traveler in Economy. Distances are in a straight line.
One-way
Los Angeles → Denver
56 km from Ontario
$39
$102 less than flying from Ontario
12 Nov · SNA → DEN · nonstop
found yesterday
Long Beach → Denver
60 km from Ontario
$152
$11 more than flying from Ontario
12 Nov · LGB → DEN · nonstop
found yesterday
Cheapest recent price on each route — one way, per traveler in Economy. Distances are in a straight line.
Live price for these dates
The cheapest return found recently is for 4 Nov – 11 Nov. A live search on this page shows what those dates cost now, for one adult in economy.
Prices are what travelers' searches on Aviasales found in the last 7 days, in US dollars: the price the seller showed on Aviasales; bags may cost extra. Fares change, so check today's price before you book. How our prices work