Ontario to London ONT → LHR
Ontario International Airport (ONT) → London Heathrow Airport (LHR)
The cheapest return found recently is $1,110 with Alaska Airlines, 26 Dec – 7 Jan 2027, found yesterday. The cheapest one-way found recently is $338 with United Airlines, 31 Jan 2027, found yesterday.
Return
The cheapest return fare on each of 9 departure dates is usually $1,025 to $1,180.
Cheapest return found recently
$1,110
26 Dec – 7 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 16 min of travel, both ways together
out 1 stop, back 1 stop
found yesterday
Cheapest nonstop return
None seen yet.
Found recently, and the cheapest we hold
$1,110 26 Dec – 7 Jan 2027found yesterdaySee prices for these dates
$740 15 Nov – 23 Novfound 6 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 $491 to $812.
At $1,110, the cheapest return 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 return price?
Compared with the cheapest return fare on each of 9 departure dates from 29 Oct to 13 Apr 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 12-night return fares leaving within 3 days of 26 Dec to compare.
Every date we hold
9 fares on 9 departure dates
See the chart as a table
| Dates | From | Airline | Airports | Stops | Found | |
|---|---|---|---|---|---|---|
| 29 Oct – 18 Dec | $1,180 | United Airlines | Ontario International Airport (ONT) → London Heathrow Airport (LHR) | out 1 stop, back 1 stop | found 5 days ago | See prices for these dates |
| 2 Nov – 18 Dec | $1,166 | United Airlines | Ontario International Airport (ONT) → London Heathrow Airport (LHR) | out 1 stop, back 1 stop | found yesterday | See prices for these dates |
| 4 Nov – 11 Nov | $1,030 | United Airlines | Ontario International Airport (ONT) → London Heathrow Airport (LHR) | out 1 stop, back 1 stop | found 4 days ago | See prices for these dates |
| 9 Nov – 13 Nov | $1,252 | United Airlines | Ontario International Airport (ONT) → London Heathrow Airport (LHR) | out 1 stop, back 1 stop | found 5 days ago | See prices for these dates |
| 15 Nov – 23 Nov | $740 | Frontier Airlines | Ontario International Airport (ONT) → London Heathrow Airport (LHR) | out 3 stops, back 2 stops | found 6 days ago | See prices for these dates |
| 15 Dec – 10 Jan 2027 | $1,025 | 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 |
| 23 Dec – 5 Jan 2027 | $1,364 | Iberia | Ontario International Airport (ONT) → London Heathrow Airport (LHR) | out 1 stop, back 1 stop | found yesterday | See prices for these dates |
| 26 Dec – 7 Jan 2027 | $1,110 | Alaska Airlines | Ontario International Airport (ONT) → London Heathrow Airport (LHR) | out 1 stop, back 1 stop | found yesterday | See prices for these dates |
| 13 Apr 2027 – 16 Apr 2027 | $821 | United Airlines | Ontario International Airport (ONT) → London Heathrow Airport (LHR) | out 1 stop, back 1 stop | found 5 days ago | See prices for these dates |
Which month looks cheapest?
November 2026 is the cheapest month — from $740.
Airlines on the cheapest dates: United Airlines, Frontier Airlines, Iberia, Alaska Airlines.
One-way
The cheapest one-way fare on each of 5 departure dates is usually $322 to $371.
Cheapest one-way found recently
$338
31 Jan 2027 · United Airlines
Ontario International Airport (ONT) → London Heathrow Airport (LHR)
Leaves 7:00 a.m. · 14 h 55 min trip
stops unknown
found yesterday
Cheapest nonstop one-way
None seen yet.
Found recently, and the cheapest we hold
$338 31 Jan 2027found yesterdayOpen this trip
$321 2 Mar 2027found 2 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 $318 to $482.
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 5 departure dates from 29 Jan 2027 to 4 Mar 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 one-way fares on 1 other departure date within 3 days of 31 Jan 2027, and it is not cheaper.
Every date we hold
6 fares on 5 departure dates
See the chart as a table
| Dates | From | Airline | Airports | Stops | Found | |
|---|---|---|---|---|---|---|
| 29 Jan 2027 | $388 | United Airlines | Ontario International Airport (ONT) → London Heathrow Airport (LHR) | 1 stop | found yesterday | Open this trip |
| 31 Jan 2027 | $338 | United Airlines | Ontario International Airport (ONT) → London Heathrow Airport (LHR) | stops unknown | found yesterday | Open this trip |
| 2 Mar 2027 | $321 | United Airlines | Ontario International Airport (ONT) → London Heathrow Airport (LHR) | 1 stop | found 2 days ago | Open this trip |
| 3 Mar 2027 | $322 | United Airlines | Ontario International Airport (ONT) → London Heathrow Airport (LHR) | 1 stop | found 4 days ago | Open this trip |
| 4 Mar 2027 | $371 | United Airlines | Ontario International Airport (ONT) → London Heathrow Airport (LHR) | 1 stop | found 4 days ago | Open this trip |
Which month looks cheapest?
March 2027 is the cheapest month — from $321.
Airlines on the cheapest dates: United 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 26 Dec – 7 Jan 2027 in another cabin: Premium economy · Business · First
Today's prices for 31 Jan 2027 in another cabin: Premium economy · Business · First
How far ahead were prices cheapest for Ontario to London?
Return
Fares 30 to 59 days before departure were typically 44% 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 | $1,260 | $1,167 | +80% | 7 |
| 7–13 days | $1,102 | $1,073 | +57% | 8 |
| 14–29 days | $922 | $740 | +31% | 22 |
| 30–59 days | $702 | $649 | Cheapest seen | 21 |
| 60–89 days | $1,076 | $818 | +53% | 23 |
| 90–179 days | $751 | $491 | +7% | 22 |
| 180+ days | $818 | $609 | +17% | 22 |
One-way
Not enough history yet: in 25 days of one-way prices, 24 Sept to 18 Oct, 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
$937
$173 less than flying from Ontario
26 Dec – 7 Jan 2027 · LAX → LHR · out 1 stop, back 1 stop
found yesterday
Long Beach → London
60 km from Ontario
$1,037
$73 less than flying from Ontario
20 Oct – 10 Nov · LGB → LHR · out 1 stop, back 1 stop
found today
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
$312
$26 less than flying from Ontario
14 Nov · LAX → LHR · stops unknown
found yesterday
Long Beach → London
60 km from Ontario
$348
$10 more than flying from Ontario
2 Mar 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 26 Dec – 7 Jan 2027. 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