$394 Cheap Flights from Ontario (ONT) to London (LHR)

Popular airlines from Los Angeles - Ontario Intl. Airport (ONT) to Heathrow Airport (LHR)

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Cheap Flights from Ontario to London (ONT-LHR)

Prices were available within the past 7 days and start at $394 for one-way flights and $598 for round trip, for the period specified. Prices and availability are subject to change. Additional terms apply.

Delta
Delta
Virgin Atlantic
Delta
United
British Airways
American Airlines
American Airlines
Delta
Delta
Flights from Ontario (ONT) to London (LHR)
Origin airport
Los Angeles - Ontario Intl.
Destination airport
Heathrow
Airlines serving
Air Canada, Air France, American Airlines, British Airways, Delta, Iberia, JetBlue Airways, KLM, United, Virgin Atlantic
Roundtrip price
$597
Distance
5409 mi

Ontario to London Flights

The cheapest times to fly from Ontario to London

On average, Thursday can be the cheapest time to fly, according to data from the Airlines Reporting Corporation (ARC), one of the world's biggest databases for global airline sales. The data reveals that you could save up to 16% by flying on a Thursday—the cheapest day to travel on average—instead of a Sunday—the most expensive. Some of the most affordable flights from Ontario to London are during the month of November. You can find some of the cheapest flights from Ontario to London with Expedia's search tool and vast selection of airlines.

The best time to book a flight from Ontario to London

Sunday is one of the best days to book for cheap flights from Ontario to London: Tickets reserved on a Sunday cost between 6% and 13% less than those reserved on a Friday, according to ARC data. The data also suggests booking early can also lead to cheaper airfares. You could save 24% by buying your tickets for domestic flights at least a month in advance and 10% by booking international flights 2 months in advance.

How to find cheap round-trip tickets from Ontario to London

Being flexible with your dates and using Expedia's Price Drop Protection and Price Tracking features are some of the best ways of finding a cheap ticket from Ontario to London in 2025. You can also book with separate airlines for your outbound and return journeys, from $394 one-way. Expedia also offers Price Drop Protection, so if the cost of your airfare goes down after booking, you'll receive a credit for the difference*. This is available for a small fee, and is free to One Key Gold and Platinum tier members.

Expedia's Price Tracking feature means you can stay on top of airfares without manually checking every day. It sends you automated price alerts for cheap Ontario to London flights and uses historical data to indicate when the best time to book is. Download Expedia's free app to activate this handy tool in a few easy taps.

You could also save big by booking one of Expedia's vacation packages. Bundling together your Ontario to London airfare with your accommodations and car rental is often cheaper than booking everything separately. There’s also One Key, Expedia's generous rewards program. Join for free and you could earn One Key cash on most bookings to save on future adventures.

*Terms apply.

Disclaimer: ARC The statistics are based on average round-trip ticket prices between January and August 2023. The percentages you see are averages.

Frequently asked questions

How much does a flight from Los Angeles - Ontario Intl. Airport (ONT) to Heathrow Airport (LHR) cost?
Discover the latest flight deals from ONT to LHR by entering your preferred travel dates and searching on Expedia. Easily compare prices by departure date if you have flexibility with your schedule and use handy filters to explore prices for your preferred journey. As a member of One Key™, our free loyalty program, you can use Price Tracking to watch fares and receive notifications if prices go up or down.
What is the cheapest month to fly from ONT to LHR?
The cheapest flights from ONT to LHR are usually during off-peak season, when demand is lower. To save money, avoid flying during public holidays, school breaks and major local events.
Which airlines fly direct from Los Angeles - Ontario Intl. Airport (ONT) to Heathrow Airport (LHR)?
You can’t fly nonstop from Ontario, CA (ONT-Los Angeles - Ontario Intl.) to Heathrow Airport (LHR). However, you can easily travel to London without any layovers by taking off from Los Angeles Intl. Airport (LAX).
What is the cheapest airline that flies from ONT to LHR?
Use the filter tool on Expedia to compare airlines and find the cheapest carrier that’ll take you from ONT to LHR. Sort your results by “Price (lowest to highest)” to snap up a great deal.
How many flights per day from Los Angeles - Ontario Intl. Airport (ONT) to Heathrow Airport (LHR)?
There aren’t any daily nonstop flights available from Los Angeles - Ontario Intl. Airport (ONT) to Heathrow Airport (LHR). But you can opt for flights with layovers. Filter your search on Expedia to include one or more stops, and you’ll be cruising above the clouds in no time at all.
What day of the week has the most flights from ONT to LHR?
You’ll generally find Tuesday the quietest day for flights, while Fridays are often the busiest.* However this can change from season to season and during peak travel times or public holidays.*Busiest/quietest day to travel is based on Expedia flight demand through January to December 2024.
What is the best time to fly from Los Angeles - Ontario Intl. Airport (ONT) to Heathrow Airport (LHR)?
To avoid potential delays on the Los Angeles - Ontario Intl. Airport (ONT) to Heathrow Airport (LHR) route, travel before 3 PM. Departures after this hour are 22% more likely to be canceled.**Most reliable time of the day and month to travel recommendation is based on January through August 2024 flight status data sourced from OAG’s global flight data platform.
Is it cheaper to buy a plane ticket from Los Angeles - Ontario Intl. Airport (ONT) to Heathrow Airport (LHR) last-minute?
Booking your flight from ONT to LHR right before your trip is generally more expensive. However, if you’re flexible with your departure times and dates, you could grab a cheap last-minute fare.
Is it cheaper to book an ONT to LHR flight and hotel package?
You’ll typically save money by booking an ONT to LHR flight and hotel package compared to booking separately. In fact, you could save hundreds of dollars by bundling with Expedia. And it’s simple to manage it all in one convenient place. Once you’ve chosen your ideal flights and accommodations, you can add extras such as tours, car rentals and activities.
Can I cancel or change the date of my flight from Los Angeles - Ontario Intl. Airport (ONT) to Heathrow Airport (LHR)?
If you booked your ONT to LHR flight within the last 24 hours, you may be able to modify or cancel it without fees. Depending on the airline and the type of fare you purchased, additional charges may apply for changes beyond this timeframe. Airline policies and contact information can be found in your itinerary or confirmation email. Or, head to our Customer Service portal if you’d like more information.

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*Available to One Key members.