ONT - LHR

$365 Find Cheap Flights from Ontario to London Heathrow Airport

This is the cheapest one-way flight price found by a KAYAK user in the last 72 hours by searching for a flight from Ontario to Heathrow departing on 4/14. Fares are subject to change and may not be available on all flights or dates of travel. Click the price to replicate the search for this deal.
1 adult
1 adult, Economy, 0 bags

KAYAK searches hundreds of travel sites at once for deals on flights to London Heathrow Airport

 
These are the airlines KAYAK users have selected most often from within our search results in flight searches from Ontario to London.
These are the airlines KAYAK users have selected most often from within our search results in flight searches from Ontario to London.
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Everything you should know

Cheapest round-trip
$648
Typical prices: $653-$782
Iberia
Tue 4/14Tue 4/28
ONT - LHR • 1 stop
Cheapest one-way
$365
Typical prices: $651-$658
Multiple Airlines
Tue 4/14
ONT - LHR • 3 stops
Top airlines
Iberia
Cheapest • from $648 (round-trip)
Delta
Best reviews • 7.9 score
Airline reviews
Airline reviews
+1
+1
Airline reviews
Airline reviews
+1
When to travel
November
Cheapest • 26% price drop
September
Most popular
Good to know
Good to know
+1
+1
Good to know
Good to know
+1
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KAYAK searches 100s of sites at once to find you the best travel deals.
We hope you love your trip to Heathrow!
Flight Deals
Booking Insights
Flight Deals

Cheap Flights from Ontario to Heathrow (ONT-LHR)

 
Here are some of the best deals found on KAYAK recently from the most popular airlines for round-trip flights from Ontario to Heathrow that are departing in the next months. While these flights were available on KAYAK in the last 72 hours, prices and availability are subject to change and deals may expire.
Discover the best prices for you by selecting your travel dates on KAYAK.

Recent round-trip flight deals from Ontario to Heathrow

Tue, Apr 14 - Tue, Apr 28
Iberia Logo
2:08 pm - 2:25 pm
ONT
-
LHR
16h 17m
1 stop
Iberia Logo
6:10 am - 8:54 pm
LHR
-
ONT
22h 44m
2 stops
$648Iberia
Wed, Apr 15 - Tue, May 5
Delta Logo
12:49 pm - 1:15 pm
ONT
-
LHR
16h 26m
1 stop
Delta Logo
9:55 am - 9:00 pm
LHR
-
ONT
19h 05m
2 stops
$649Delta
Wed, Apr 15 - Tue, May 5
Delta Logo
1:29 pm - 1:15 pm
ONT
-
LHR
15h 46m
2 stops
Delta Logo
8:40 am - 9:00 pm
LHR
-
ONT
20h 20m
2 stops
$653Delta
Sat, Apr 18 - Thu, Apr 30
United Airlines Logo
6:49 pm - 7:25 am
ONT
-
LHR
28h 36m
1 stop
United Airlines Logo
2:05 pm - 8:36 pm
LHR
-
ONT
38h 31m
2 stops
$658United Airlines
Mon, May 4 - Tue, May 19
United Airlines Logo
7:00 am - 11:45 am
ONT
-
LHR
20h 45m
1 stop
United Airlines Logo
9:30 am - 9:58 pm
LHR
-
ONT
20h 28m
2 stops
$660United Airlines
Wed, Mar 18 - Tue, Mar 24
Delta Logo
1:20 pm - 10:00 am
ONT
-
LHR
13h 40m
1 stop
Delta Logo
10:45 am - 11:51 pm
LHR
-
ONT
20h 06m
1 stop
$661Delta
Tue, Mar 17 - Mon, Mar 23
United Airlines Logo
1:40 pm - 12:00 pm
ONT
-
LHR
15h 20m
1 stop
United Airlines Logo
10:05 am - 5:41 pm
LHR
-
ONT
14h 36m
1 stop
$662United Airlines
Tue, Mar 3 - Wed, Mar 11
Delta Logo
1:10 pm - 10:00 am
ONT
-
LHR
12h 50m
1 stop
Delta Logo
6:30 am - 5:12 pm
LHR
-
ONT
17h 42m
2 stops
$663Delta
Mon, Mar 23 - Thu, Apr 2
Delta Logo
11:59 am - 11:55 am
ONT
-
LHR
16h 56m
1 stop
Delta Logo
6:30 am - 11:51 pm
LHR
-
ONT
25h 21m
2 stops
$664Delta
Wed, Apr 15 - Tue, May 5
United Airlines Logo
7:00 am - 8:20 am
ONT
-
LHR
17h 20m
2 stops
United Airlines Logo
9:30 am - 9:58 pm
LHR
-
ONT
20h 28m
2 stops
$665United Airlines
Booking Insights

KAYAK's insights & trends for Ontario to Heathrow flights

Get data-powered insights and trends into flights from Ontario to Heathrow to help you find the cheapest flights, the best time to fly and much more.

How much is a round-trip flight from Ontario to London Heathrow Airport?

This analysis is based on the cheapest round-trip price found on KAYAK in the last 12 months by searching for a flight from Ontario to London Heathrow Airport departing in April.

What is the cheapest month to fly from Ontario to London Heathrow Airport?

To calculate monthly average prices, KAYAK takes all prices for each month over the last year for round-trip flights from Ontario to London Heathrow Airport, removes the top 0.1% to account for outliers, and then takes the median of all values for each month.

The cheapest month for flights from Ontario to London Heathrow Airport is November, where tickets cost $624 (return) on average. On the other hand, the most expensive months are June and July, where the average cost of round-trip tickets is $1,356 and $1,009 respectively.

Good to know

Low seasonJanuary
Cheapest flight$365
Best time to beat the crowds but there is an average 13% increase in price.
Most popular time to fly and prices are also 19% lower on average.
Flight from Ontario to London Heathrow Airport

When to book flights from Ontario to Heathrow

Are your dates flexible? Find out the best times to travel from Ontario to Heathrow based on our flight data from the last year. Discover the cheapest month and even day to fly.
Estimated round-trip price
KAYAK looks at all historical flight data for each date to provide a predicted price for one-way trips or round-trips with a duration up to 40 days. While we try to provide actual minimum prices for each date, some prices are predictions and actual prices may differ.

FAQs for booking Ontario to London Heathrow Airport flights

  • What is the cheapest flight from Ontario to London Heathrow Airport?

    In the last 3 days, the lowest price for a flight from Ontario to London Heathrow Airport was $365 for a one-way ticket and $648 for a round-trip.

  • Do I need a passport to fly between Ontario and London Heathrow Airport?

    A passport is required to fly from Ontario to London Heathrow Airport.

  • Which aircraft models fly most regularly from Ontario to London Heathrow Airport?

    We unfortunately don’t have that data for this specific route.

  • Which airline alliances offer flights from Ontario to London Heathrow Airport?

    SkyTeam, Star Alliance, and oneworld are the airline alliances operating flights between Ontario and London Heathrow Airport, with SkyTeam being the most commonly used for this route.

  • Which is the best airline for flights from Ontario to London, Delta or KLM?

    The two airlines most popular with KAYAK users for flights from Ontario to London are Delta and KLM. With an average price for the route of $671 and an overall rating of 7.9, Delta is the most popular choice. KLM is also a great choice for the route, with an average price of $653 and an overall rating of 7.7.

  • How does KAYAK find such low prices on flights from Ontario to London Heathrow Airport?

    KAYAK is a travel search engine. That means we look across the web to find the best prices we can find for our users. With over 2 billion flight queries processed yearly, we are able to display a variety of prices and options on flights from Ontario to London Heathrow Airport.

  • How does KAYAK's flight Price Forecast tool help me choose the right time to buy my flight ticket from Ontario to London Heathrow Airport?

    KAYAK’s flight Price Forecast tool uses historical data to determine whether the price for a flight to London Heathrow Airport from Ontario is likely to change within 7 days, so travelers know whether to wait or book now.

  • What is the Hacker Fare option on flights from Ontario to London Heathrow Airport?

    Hacker Fares allow you to combine one-way tickets in order to save you money over a traditional round-trip ticket. You could then fly to London Heathrow Airport with an airline and back to Ontario with another airline. Booking your flights between Ontario and LHR can sometimes prove cheaper using this method.

  • What is KAYAK's "flexible dates" feature and why should I care when looking for a flight from Ontario to London Heathrow Airport?

    Sometimes travel dates aren't set in stone. If your preferred travel dates have some wiggle room, flexible dates will show you all the options when flying to London Heathrow Airport from Ontario up to 3 days before/after your preferred dates. You can then pick the flights that suit you best.

Reviews of the top 5 airlines serving from Ontario to Heathrow

 
See real verified KAYAK customer reviews for airlines flying from Ontario to London. Airline scores are aggregated from all reviews left by passengers on KAYAK after flying with an airline. KAYAK doesn’t show reviews that are older than 5 years. Learn how KAYAK collects reviews.
Need help choosing which airline to fly with from Ontario to Heathrow? KAYAK airline reviews give an overall score for each airline based on loads of factors, including comfort, boarding, in-flight entertainment and more, to make your decision easier. See airline scores according to verified KAYAK customer reviews.
7.9
DeltaOverall score based on 8208 reviews
8.5Crew
7.9Comfort
7.2Food
8.1Boarding
7.8Entertainment
Airline reviews

The crew, and fellow passengers, were super gracious and kind. There seemed to be plenty of bin space even though the plane was full. It’s nice to get a glass of wine with dinner in Premiere seating, and there was a lot of food.

10.0 ExcellentGrace, Feb 2026
LAX - JFK
Read more Delta reviews

The crew, and fellow passengers, were super gracious and kind. There seemed to be plenty of bin space even though the plane was full. It’s nice to get a glass of wine with dinner in Premiere seating, and there was a lot of food.

Everything I mentioned earlier - the airbus was more comfortable indeed and the experience was further enhanced.

The plane was an older model, so it wasn’t as comfortable as others. The flight attendants were not helpful during onboarding. It was a full flight so there was chaos finding space for baggage.

Awesome! On time flight, early arrival, and a complimentary upgrade!

It was nt delta. It was aeromexo. Service was awful. They served a very small drink and NO snack for a 3hr and 35min flight. Then for the first 30 min of the flight is was talk and talk over head interruption the movie/ show i picked to watch.

Delta One is extraordinary. I fly business when somebody hires me. I just wonder why there is such a chasm between business class and the insanely inhumane and nonsensical coach. The seats are not large enough to fit even my tiny wife. We fly 10% of what we did because we don’t want to pay 5-10 k but for $400 it’s unbearable. It seems like the accountants took over and made stupid decisions. Screw in 20 extra seats and make it so unbearable that people fly 90% less. Just put the damn price up and put some proper chairs in. But business, yay.

Delta’s staff is unmatched. From the gate agents, to the pilots, to the flight attendants… all top of the industry.

The flight was delayed for about 2 hrs. Other than it, it was good.

I am extremely disappointed that delta internal pilot manuals now refer to the Gulf of Mexico as the “gulf of America”. You can bow down to the Orange turd on your own. I will never fly delta again

No lunch on a x-country flight scheduled for 10:50 am departure, arrived 5+ hrs later. That requires a black box label before you pay for the tickets. Worst, when I checked in online, it's specifically said that lunch was served on his flight for economy Plus passengers.

Empty seats next to me - wish it had been for a longer flight!!

Flight was on time, staff are friendly and helpful onboard.

Delay and had to run between flight to get my connection due to this delay but besides that the overall experience was ok. I arrived with just an hour of delay.

They forgot to serve food and the crew was very unfriendly. Never experienced such a bad KLM flight. Usually fly from Toronto. New York was different.

Over 1 Hr delay. No APU so no AC on ground. Plane was hot during boarding and then they closed the doors over 20 minutes before engine start so interior of plane was steamy hot and stuffy. Could have been helped by opening doors until ready to depart.

First of all we couldn’t check in online, then we learn at the airport we were on stand by for KLM’s mistake of overbooking. The seats were not comfy at all. Our luggage got lost.

Ad experience - been flying many years with them but they are losing out to other carriers with their service and bagage / seating policy. My 2 12-yo kids were not placed with the parent. Absurdity.

KLM remains a quality flag carrier airline which maintains its standards whilst all their competitors are lowering theirs.

Our first flight was delayed so we missed our connecting flight. However it was easy to book a later flight on their app.

My flight was delayed by 6 hours then I missed BOTH of my connecting flights, I then had to stay in the AIRPORT at JFK because soooooo many people also suffered from missing flights and there was no hotels available. I would like to be compensated for this experience! I had to stay in the airport for over 16 hours!

Entertainment kept turning itself off. Gave up on watching a movie.

Very disappointing given gate agent behavior. Filed a formal complaint with United.

Crew was great (professional, attentive, prompt). Snacks for 4 hrs flight is deplorable.

Flight delayed. WiFi connectivity very poor if not existant. Last minute arrival forced me to run to catch my connection.

Terrible. No customer service, no food, no drinks on a 6 hour premier economy booking.

Check-in and in-flight staff were better than average. The seat was a fair size but too hard and not enough padding. The cushion/pillow provided is poor (thin and seems to be disposable ,it provides no effective cushioning or support). Food was OK-ish but no choice of inflight snacks and no easy place to get drinks other than water (I could ask for juice by intruding into the staff area at the back of the plane) Entertainment was very good actually. Overall better than I expected from a US-based airline (sorry!) but compared to ANA or Singapore it was so-so. (I live in Japan so they are my comparative airlines)

Terrible. Our first time back on United for 10 years, the seats in Polaris class are small and uncomfortable. They have squished too many people in to get more $$$. The staff are not friendly and not wanting to accommodate. I asked for two salads rather than a main meal and was advised no we wont do that. Then asked what I would like for breakfast and given something else anyway. I will not be flying United International anytime soon.

The food was terrible this time. Otherwise pleasant, quiet, on-time.

It was a pretty standard flight... until the almost hour and a half spent on the taxi way. I get that the weather has been poor but the delay had nothing to do with the weather and more to do with a plane with several issues tying up the gate. I get that that happens from time to time but this has been EVERY flight I've been on for the past 5 years and I fly 3 to 5 times a year. This isn't just United... it's American, it's Delta. It's an issue with the entire industry. I work for UPS and packages on a cargo plane get better service than people do these days. Anymore I HATE flying.

The flight crew where really good. Better then the crew from BNE to SFO

My flight to London from Philadelphia was cancelled due to weather.

Disliked having to wait a little longer to disembark from the plan when we landed in London

Food should be better quality. Video screens have poor resolution and the library of movies is poor. The other airlines are much better.

The trip was smooth but the crew were very abrupt, snatching things before finished and being quite snappy when asked questions.

My wife and I love to travel, so we fly a lot. We've already logged 381,075 miles and with practically every major airline. But this flight was very disappointing. It started off well, with no delays and a new plane. But when lunchtime approached, all that good impression was ruined. Instead of white tablecloths, we were offered small, dark placemats, which, as it turned out, were perfectly adequate for the food. All the food offered—and my wife and I only took fish, and the meat—was not just bad, it was downright disgusting and not heated enough. The same applies to the appetizers. This was the first time in many years of traveling that we've been offered such disgusting food.

Lost luggage stuck no clothes and no word after 2 days leaving on cruise no stuff or clothes

Don’t know they cancelled the flight day before I was to leave. They sent a email at 9:00 pm at night saying they cancelled. That is the smooth way to say we don’t want your business! I think they didn’t have enough people booking so they cancelled the flight! It’s all about the money anymore there is no honesty in business.

The flight was canceled 3 hours after original take off time

Pathetic check in experience at JFK. Everything is self check in. Not enough staff present to help with when the check in process or the kiosk gets stuck. Staff present not welcoming or pleasant at all. On the other hand the NY based flight crew was great. Courteous and friendly throughout the flight. Special meals leave a lot to be desired. Kids meals should be made available when kids are flying and same goes for special kids meals too.

Flight was full, and would have preferred an aisle seat, but due to getting a late ticket ,the seat I had was adequate. The flight crew were very help full and hard working. Food and drink were excellent for the 11hr flight. Overall I was pleased with flight, and would recommend British Airways again.

They had us seating down for one hour just waiting on the plane

Flying with BA is always a good experience—even in economy class. It is better if in business and first class. Timely, breeze through security and timely connections

We waited at BOS at the gate for an hour and couldn’t get a drink or anything. Once in the air the service, food and ride was excellent.

My enetertainmnet screen was broken. Lost my bags. Almost missed my flight do to connection issues with (despite a request) ZERO help from crew. Food was edible. Potatoes pretty good even

The issue was not with BA it was with the link yoiu sent fopr booking the flight

Loved the boarding option from Business class lounge, experience on flight was excellent, plenty of good food choices

The airline was not clear about a new departure time so we got to the airport early anyway. The flight left early which was great because of weather. The check in process was very easy and staff were friendly and helpful. The crew was great and our flight was very good.

Awful it always is unfortunately is the only way to fly direct to london

I travelled in business class and was disappointed by lack of service, curt and borderline rude time of the crew and to top it off, all of my luggage was delayed. It was like pulling teeth to even report the missing luggage and recover it the next day from the airport.

Boarding was poor. All groups called immediately one after the other resulting in a long queue in the jetty/jet bridge. Seats were very hard and and did not recline on a 4.5 hour flight. No food was available. Plane was cold. There was no entertainment.

Everything you need to know for your flight from Ontario to Heathrow

Information on your arrival and departure airports