Cheap flights from Ontario to London from $326 ONT → LHR
Ontario International Airport (ONT) → London Heathrow Airport (LHR)
The cheapest return found recently is $991 with Alaska Airlines, 17 Jan 2027 – 19 Jan 2027, found 2 days ago. The cheapest one-way found recently is $326 with United Airlines, 4 May 2027, found 2 days ago.
- Cheapest one-way found recently
- $326, found 2 days ago
- Cheapest return found recently
- $991, 17 Jan 2027 to 19 Jan 2027
- Usual return price
- $874 to $1,188
- Cheapest month to fly
- April 2027, return fares from $801 found in the last 7 days
Return
The cheapest return fare on each of 14 departure dates is usually $874 to $1,188.
Cheapest return found recently
$991
17 Jan 2027 – 19 Jan 2027 · Alaska Airlines
Ontario International Airport (ONT) → London Heathrow Airport (LHR)
Leaves 6:00 a.m. · Return leaves 2:45 p.m. · 38 h 18 min of travel, both ways together
out 1 stop, back 1 stop
found 2 days ago
Cheapest nonstop return
None seen yet.
Found recently, and the cheapest we hold
$991 17 Jan 2027 – 19 Jan 2027found 2 days agoSee prices for these dates
$801 13 Apr 2027 – 16 Apr 2027found 6 days agoSee prices for these dates
What have prices looked like?
Over 49 days, 24 Sept to 11 Nov, the cheapest return we saw each day was $491 to $899.
At $991, the cheapest return found recently is above that range.
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 14 departure dates from 30 Nov to 13 Sept 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?
No. We hold 2-night return fares on 2 other departure dates within 3 days of 17 Jan 2027, and none is cheaper.
Every date we hold
15 fares on 14 departure dates
See the chart as a table
| Dates | From | Airline | Airports | Stops | Found | |
|---|---|---|---|---|---|---|
| 30 Nov – 13 Dec | $1,071 | United Airlines | Ontario International Airport (ONT) → London Heathrow Airport (LHR) | out 1 stop, back 1 stop | found 2 days ago | See prices for these dates |
| 13 Dec – 18 Dec | $1,388 | United Airlines | Ontario International Airport (ONT) → London Heathrow Airport (LHR) | out 1 stop, back 1 stop | found 3 days ago | See prices for these dates |
| 26 Dec – 31 Dec | $1,539 | United Airlines | Ontario International Airport (ONT) → London Heathrow Airport (LHR) | out 1 stop, back 1 stop | found 3 days ago | See prices for these dates |
| 28 Dec – 1 Jan 2027 | $1,567 | Iberia | Ontario International Airport (ONT) → London Heathrow Airport (LHR) | out 1 stop, back 1 stop | found 3 days ago | See prices for these dates |
| 17 Jan 2027 – 19 Jan 2027 | $991 | Alaska Airlines | Ontario International Airport (ONT) → London Heathrow Airport (LHR) | out 1 stop, back 1 stop | found 2 days ago | See prices for these dates |
| 18 Jan 2027 – 20 Jan 2027 | $1,018 | Alaska Airlines | Ontario International Airport (ONT) → London Heathrow Airport (LHR) | out 1 stop, back 1 stop | found 2 days ago | See prices for these dates |
| 19 Jan 2027 – 21 Jan 2027 | $991 | Alaska Airlines | Ontario International Airport (ONT) → London Heathrow Airport (LHR) | out 1 stop, back 1 stop | found 2 days ago | See prices for these dates |
| 11 Apr 2027 – 15 Apr 2027 | $831 | United Airlines | Ontario International Airport (ONT) → London Heathrow Airport (LHR) | out 1 stop, back 1 stop | found 3 days ago | See prices for these dates |
| 13 Apr 2027 – 16 Apr 2027 | $801 | United Airlines | Ontario International Airport (ONT) → London Heathrow Airport (LHR) | out 1 stop, back 1 stop | found 6 days ago | See prices for these dates |
| 14 Apr 2027 – 21 Apr 2027 | $844 | United Airlines | Ontario International Airport (ONT) → London Heathrow Airport (LHR) | out 1 stop, back 1 stop | found 3 days ago | See prices for these dates |
| 15 Apr 2027 – 19 Apr 2027 | $855 | United Airlines | Ontario International Airport (ONT) → London Heathrow Airport (LHR) | out 1 stop, back 1 stop | found 3 days ago | See prices for these dates |
| 28 May 2027 – 1 Jun 2027 | $1,054 | jetBlue | Ontario International Airport (ONT) → London Heathrow Airport (LHR) | out 1 stop, back 1 stop | found 3 days ago | See prices for these dates |
| 12 Sept 2027 – 7 Oct 2027 | $929 | United Airlines | Ontario International Airport (ONT) → London Heathrow Airport (LHR) | out 2 stops, back 1 stop | found 5 days ago | See prices for these dates |
| 13 Sept 2027 – 8 Oct 2027 | $1,227 | Alaska Airlines | Ontario International Airport (ONT) → London Heathrow Airport (LHR) | out 1 stop, back 3 stops | found 5 days ago | See prices for these dates |
Which month looks cheapest?
April 2027 is the cheapest month — from $801.
Airlines on the cheapest dates: United Airlines, Alaska Airlines, Iberia, jetBlue.
One-way
The cheapest one-way fare on each of 3 departure dates is usually $326 to $361.
Cheapest one-way found recently
$326
4 May 2027 · United Airlines
Ontario International Airport (ONT) → London Heathrow Airport (LHR)
Leaves 1:00 p.m. · 12 h 40 min trip
1 stop
found 2 days ago
Cheapest nonstop one-way
None seen yet.
Found recently, and the cheapest we hold
$326 4 May 2027found 2 days agoOpen this trip
It is also the cheapest one-way we hold, of any age.
What have prices looked like?
Over 39 days, 24 Sept to 11 Nov, the cheapest one-way we saw each day was $318 to $495.
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 3 departure dates from 4 May 2027 to 13 Sept 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 one-way fares leaving within 3 days of 4 May 2027 to compare.
Every date we hold
4 fares on 3 departure dates
See the chart as a table
| Dates | From | Airline | Airports | Stops | Found | |
|---|---|---|---|---|---|---|
| 4 May 2027 | $326 | United Airlines | Ontario International Airport (ONT) → London Heathrow Airport (LHR) | 1 stop | found 2 days ago | Open this trip |
| 27 Aug 2027 | $395 | Alaska Airlines | Ontario International Airport (ONT) → London Heathrow Airport (LHR) | 1 stop | found 5 days ago | Open this trip |
| 13 Sept 2027 | $326 | United Airlines | Ontario International Airport (ONT) → London Heathrow Airport (LHR) | 1 stop | found 5 days ago | Open this trip |
Which month looks cheapest?
May 2027 is the cheapest month — from $326.
Airlines on the cheapest dates: United Airlines, Alaska Airlines.
Premium cabin fares from Ontario to London
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 17 Jan 2027 – 19 Jan 2027 in another cabin: Premium economy · Business · First
Today's prices for 4 May 2027 in another cabin: Premium economy · Business · First
How far ahead were prices cheapest for Ontario to London?
Return
Fares 90 to 179 days before departure were typically 25% 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.
See these ranges as a table
| Booked ahead by | Typical fare | Cheapest day | Above the cheapest | Days of prices |
|---|---|---|---|---|
| 0–6 days | $1,069 | $1,019 | +34% | 21 |
| 7–13 days | $1,073 | $1,019 | +34% | 28 |
| 14–29 days | $926 | $740 | +16% | 46 |
| 30–59 days | $878 | $649 | +10% | 43 |
| 60–89 days | $1,093 | $818 | +37% | 34 |
| 90–179 days | $801 | $491 | Cheapest seen | 43 |
| 180+ days | $851 | $609 | +6% | 39 |
One-way
Not enough history yet: in 39 days of one-way prices, 24 Sept to 11 Nov, fewer than 3 booking ranges had prices on 7 days or more.
Could a nearby airport be cheaper?
A different airport at either end can change the fare — sometimes a lot.
Return
Los Angeles → London
56 km from Ontario
$612
$379 less than flying from Ontario
19 Jan 2027 – 21 Jan 2027 · LAX → LGW · out 1 stop, back 1 stop
found 2 days ago
Long Beach → London
60 km from Ontario
$991
The same price as flying from Ontario
17 Jan 2027 – 19 Jan 2027 · LGB → LHR · out 1 stop, back 1 stop
found 2 days ago
Cheapest recent price on each route — round trip, per traveler in Economy. Distances are in a straight line.
One-way
Los Angeles → London
56 km from Ontario
$290
$36 less than flying from Ontario
8 Jan 2027 · LAX → LHR · 1 stop
found 3 days ago
Long Beach → London
60 km from Ontario
$439
$113 more than flying from Ontario
4 May 2027 · LGB → LHR · 1 stop
found 2 days ago
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 17 Jan 2027 – 19 Jan 2027. A live search on this page shows what those dates cost now, for one adult in economy.
Questions about this trip
How much is a return flight from Ontario to London?
The cheapest return found recently is $991 with Alaska Airlines, 17 Jan 2027 to 19 Jan 2027, found 2 days ago. The cheapest return we hold, of any age, is $801 with United Airlines, 13 Apr 2027 to 16 Apr 2027, found 6 days ago. The cheapest return fare on each of 14 departure dates is usually $874 to $1,188.
How much is a one-way flight from Ontario to London?
The cheapest one-way found recently is $326 with United Airlines, 4 May 2027, found 2 days ago. The cheapest one-way fare on each of 3 departure dates is usually $326 to $361.
What is the cheapest month to fly from Ontario to London?
April 2027 is the cheapest month for a return, from $801, 13 Apr 2027 to 16 Apr 2027, found 6 days ago. May 2027 is the cheapest month for a one-way, from $326, 4 May 2027, found 2 days ago.
How far ahead should I book a flight from Ontario to London?
In 49 days of prices between 24 Sept and 11 Nov, return fares 90 to 179 days before departure were typically 25% lower than 0 to 6 days before departure.
How long is the flight from Ontario to London?
The cheapest one-way found recently, with United Airlines on 4 May 2027, takes 12 h 40 min with 1 stop.
Which airlines have the cheapest flights from Ontario to London?
Between 30 Nov and 13 Sept 2027, United Airlines has the cheapest return on 8 of the 14 departure dates we hold, Alaska Airlines on 4 and Iberia on 1. Between 4 May 2027 and 13 Sept 2027, United Airlines has the cheapest one-way on 2 of the 3 departure dates we hold, and Alaska Airlines on 1.
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