ONT - LHR

$322 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 10/1. 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

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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Flights 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

Sun, Jul 13 - Tue, Aug 5
Delta Logo
2:25 pm - 2:15 pmONT-LHR
15h 50m1 stop
Delta Logo
10:55 am - 11:42 pmLHR-ONT
20h 47m1 stop
$610Delta
Find Deal
Sun, Jul 27 - Thu, Aug 7
Delta Logo
11:25 am - 2:15 pmONT-LHR
18h 50m1 stop
Delta Logo
6:30 am - 5:16 pmLHR-ONT
18h 46m2 stops
$639Delta
Find Deal
Sun, Oct 5 - Tue, Oct 14
Iberia Logo
2:30 pm - 2:25 pmONT-LHR
15h 55m1 stop
Iberia Logo
6:10 am - 12:02 amLHR-ONT
25h 52m2 stops
$657Iberia
Find Deal
Tue, Aug 12 - Tue, Sep 2
British Airways Logo
2:57 pm - 2:25 pmONT-LHR
15h 28m1 stop
British Airways Logo
11:30 am - 10:48 pmLHR-ONT
19h 18m2 stops
$659British Airways
Find Deal
Wed, Aug 13 - Tue, Sep 2
British Airways Logo
2:57 pm - 2:25 pmONT-LHR
15h 28m1 stop
British Airways Logo
11:30 am - 10:48 pmLHR-ONT
19h 18m2 stops
$660British Airways
Find Deal
Sun, Aug 3 - Tue, Aug 19
American Airlines Logo
4:45 pm - 12:50 pmONT-LHR
12h 05m1 stop
American Airlines Logo
11:15 am - 5:52 pmLHR-ONT
14h 37m1 stop
$672American Airlines
Find Deal
Sun, Aug 3 - Tue, Aug 19
American Airlines Logo
4:45 pm - 12:50 pmONT-LHR
12h 05m1 stop
American Airlines Logo
12:00 pm - 6:24 pmLHR-ONT
14h 24m1 stop
$673American Airlines
Find Deal
Mon, Sep 1 - Wed, Sep 10
United Airlines Logo
1:42 pm - 10:25 amONT-LHR
12h 43m1 stop
United Airlines Logo
2:50 pm - 8:43 pmLHR-ONT
13h 53m1 stop
$681United Airlines
Find Deal
Tue, Oct 28 - Fri, Nov 7
United Airlines Logo
1:00 pm - 11:15 amONT-LHR
15h 15m2 stops
United Airlines Logo
10:05 am - 5:34 pmLHR-ONT
15h 29m1 stop
$685United Airlines
Find Deal
Mon, Sep 8 - Tue, Sep 23
Iberia Logo
12:47 pm - 10:50 amONT-LHR
14h 03m1 stop
Iberia Logo
10:30 am - 7:00 pmLHR-ONT
16h 30m1 stop
$716Iberia
Find Deal
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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.

What’s the cheapest day of the week to fly from Ontario to London Heathrow Airport?

The average price of all round-trip flights from Ontario to London Heathrow Airport clicked on KAYAK for each day over the last 12 months.

If your flying dates are flexible, you should consider flying to London Heathrow Airport on a Wednesday, as we generally find the cheapest rates on that day for this route. On the other hand, Saturday is the most expensive day to fly from Ontario to London Heathrow Airport. For your return ticket, we recommend flying on a Tuesday and avoiding Mondays for the best deals.

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 March, where tickets cost $669 (return) on average. On the other hand, the most expensive months are June and July, where the average cost of round-trip tickets is $1,317 and $1,027 respectively.

How far in advance should I book a flight from Ontario to London Heathrow Airport?

To calculate weekly average prices, KAYAK takes all prices for each week before departure 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 average of all the values for each week.

To get a below average price on the flight from Ontario to London Heathrow Airport, you should book around 3 weeks before departure. For the absolute cheapest price, our data suggests you should book 16 weeks before departure.

Good to know

Low seasonFebruary
High seasonAugust
Cheapest flight$322
Best time to beat the crowds with an average 19% drop in price.
Most popular time to fly with an average 1% increase in price.
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 $322 for a one-way ticket and $610 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 Star Alliance 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 $791 and an overall rating of 8.0, Delta is the most popular choice. KLM is also a great choice for the route, with an average price of $763 and an overall rating of 7.8.

  • 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.

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.
8.0
DeltaOverall score based on 7946 reviews
7.9Entertainment
7.9Comfort
7.3Food
8.2Boarding
8.5Crew
Airline reviews

It would be nice if was given wires ear buds. Overall was a good experience was able to sleep on the plane

10.0 ExcellentIrene, Jun 2025LAX - HNL
Read more Delta reviews

It would be nice if was given wires ear buds. Overall was a good experience was able to sleep on the plane

737-800 in first class was pretty dumpy. Seat had an uncomfortable angle, storage under the seat was blocked so even my very modest backpack didn't fit, power outlet was flaky. Weird tiny seat pockets that couldn't hold a gallon ziploc bag, emesis bag missing, etc. etc. No in-flight service due to turbulence. Crew was excellent, boarding was smooth despite a full flight.

Delta flight was on time, seats were comfortable, and crew was nice.

Bathrooms dirty sinks clogged. No one seemed to clean them. Plane very old

Thank you for not flipping the plane on the run way. You guys get a 5 star rating for the flight!!!

Boarding is, as it always is… horrible. Gate lice. Slow moving zones. Too many people with carry ons

It was terrible, if they ran flights on time it would make a big difference.

Delta seems to be improving in many areas, except they are super bad with the food available. Bring back normal food service on long flights.

All fine save for the abominable catering. Really gone downhill. We found it all inedible.

I actually received a notification from kayak on email but not one by text from Delta when my departure gait changed and I almost missed my flight

it was so bad. I tried to board my flight from vancouver to saskatoon. And to my surprise they did not board me cause the flight was changed and no email was send to me. and on my boarding pass which i got from seattle says different flight. I did not knew anyone from Vancouver, air canada crew was rude, i asked for today flight but they were rude and i had early morning dental appointment in saskatoon. I was so much in pain and my whole day is wasted today. and i suffered alot. They did provide me hotel but they did not provide me any food. I am really really disappointed first time had so bad experience with air canada. I may think twice to book it again. If i can get any reply or any composition that would be great. Thanks

Very comfortable (upgraded to business class). The audio on my screen didn’t work, but I managed to play the audio through my phone while watching the screen.

The food was the worst I’ve had on any flight I’ve ever been on.

I was supposed to be on business class at first class from Denver back to Miami due to weather changes. I missed my connection and it’s put on a flight to Fort Lauderdale. Instead of honoring my business class/1st class ticket, they put me in coach, but there were two first class seats open. I think it’s absolutely disgusting that I paid for first class $1300 ticket and they put me in economy and they had to open seats available and I have still not been refunded the difference. I ended up having to eat a snack box instead of the meal I was supposed to get and did not get home till 2 AM so I think that’s a little pathetic that I had to live off crackers for dinner And my poor dog ate some cheese and salami. Oh yes, apparently when they switched me to the new flight they forgot to mention I had a service dog

Flight was late as pilot crew had to land at different airport in their previous flight. Passengers boarded and had to wait for pilots inside plane. Series of incomplete and unnecessary announcements by an annoying voice, rather than complete, informative announcements.

Breakfast was not loaded at SFO due to catering company change. Seems like a major airline at a major hub would have thought of something else or warned passengers to pick up food before boarding a 3 hour flight.

Boarding seemed to be organized bedlam. For what ever reason, preboarding took longer than 20 minutes. Made the plane 20 minutes late taking off. Luckily we arrived on time. Flight crew seemed very friendly. Only slight turbulence.

They hired a new catering company the same day of my flight. They botched the job by not delivering the right carts and after THREE HOURS waiting, the flight crew timed out (flight was 19 hours long and FAA rules state crew can’t work more than 14 hours long). So they CANCELED OUR FLIGHT!! Worst experience ever. Avoid UAL at all costs.

The personnel were professional and friendly. The Boeing 737 Max 9 is too claustrophobic and was very warm at both airport gates, and still warm in the air.

While the staff was pleasant and helpful, the following observations are for your awareness. There was some delay on the tarmac on take off and landing. The paid lunch/food offerings were limited. Entertainment was only available on WiFi at a cost.

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.

More choices on menu. Seemed only thing offered was Scottish, and while that’s good for the Scot’s it doesn’t help the Americans who don’t like that food. And I really hate it when, during sleep time the attendants have a very loud conversation right over you. Lastly, I paid 5000 dollars for business class, and having to pay more to choose my seat early is really an insult. Seems greedy

More choices on menu. Seemed only thing offered was Scottish, and while that’s good for the Scot’s it doesn’t help the Americans who don’t like that food. And I really hate it when, during sleep time the attendants have a very loud conversation right over you

The chicken adobo was a little too spicy but good otherwise. My personal opinion. Movie selection could be improved, too many horror movies. Could add a few more chick flicks! The flight was bumpy at times. We arrived a little early too! Flight attendants friendly.

Again flight was awesome except British Airways lost both gate checked luggage’s. Still missing

really bad they refused to check in luggages that I had purchased, even showing them the transaction receipt from british airways app the staff in miami was MEDIOCRE

Crew was great and responsive. Entertainment quit working with about 4 hours remaining on the flight. My seat cushion was broken.

Not very good , the stewardess were unfriendly and they don't like to be bothered. Cos was a night flight and they need to sleep.

British Airways staff are very polite and willing to help.

This particular flight wasn't very full at the back, so there were three seats available for spreading out and getting relatively comfortable

From boarding, to attention in flight, I couldn’t fault it.

Not having to check carry on bags when plane wasn’t full. (The told us it was)

I was in business class for the 8 hour flight where: 1. The WiFi did not work 2. The entertainment system did not work 3. We were told there were no hot drinks for the entire flight

I had an issue with the name on my ticket vs my passport name. I was very upset that the Iberia ticket clerk had no authorization to help me and I was left to fix it. It took 19 calls of persons promising to accomplish and not doing anything before I reached someone who helped me in 10 minutes. Two of them even hung up on me. I missed my original flight because of this. Terrible customer service.

The flight was delayed twice. When the crew explained about the debris causing flat tires, I was glad they took the time to change all four.

My carry-on bag was taken from me when I boarded. It was checked through to London at no charge. It took a big of shuffling, but I was glad not to need to mind it until baggage claim.

Flight boarded three hours late for no reason other than someone made a huge error in crew scheduling. We missed our connecting flight in Madrid and got zero help from American or Iberian airlines on rebooking. We had to pay for a car to take us to the Madrid train station and pay for train tickets to Santiago. We never used our booked flight to Santiago. American claims I can submit the expenses but they are not obligated to cover them. Very frustrating.

Flight delayed Service could be better Iberia staff are not really friendly

They cancelled the flight)(they said bad weather but many other flights took off) and made us wait 5 hours in line to figure out what to do. We ended up making a new flight the next day on another airlines...I hope they honor giving us our money back

Awful. The flight wasn't actually operated by Iberia, but by American Airlines. I was unable to get my boarding pass and as a result missed my connecting flight.

The payment system was not working so was unable to connect wifi the entire flight

everything to do with KAYAK was terrible. Your customer facing departments are utterly useless, timewasting and unhelpful.

I ordered short ribs for main course. It tasted sweet, really sweet. Horrible.

The screen didn’t work and I didn’t get the seat upgrade I paid $300 for. They were no help with that,

Paid $180 for seat selection, and selection essnt honored. Have to call for a refund.

My flights were great and the crew on them was lovely especially the London to Barcelona flight as Al & AJ were so amazingly nice. I wish they would be my crew always as they have the best customer service. Sadly both flights were delayed the first one from Vegas was because they clearly loaded the cargo wrong the plane was off balance making us 2 hours late. This made me miss my connection and sadly it was challenging rebooking while I was on the flight. I will never use Kayak again as there was no customer service number or live chat and you rebooked me on a flight 2 days later. I had my mom call BA to change it which she did after spending an hour on hold. This should not be so difficult. My second flight was an hour delayed due to not being able to disconnect the bridge from the plane but I did finally make it home.

The delay was not communicated via text and the person who helped with check in also didn’t inform me about the delay. I ended up missing my connection and it was a waste of 5 hours. The crew didn’t mention there would be someone at the gate informing of if I would be rebooked and there was no signage. Overall a very poor experience. The British Airways app was also very buggy, and didn’t work. I will avoid flying with British Airways when possible.

A little better than outward journey but mild chaos at the boarding gate because some people with boarding cards from connecting flights had cards which weren't recognised

The BA business class cabin is excellent,very comfortable for sleeping but the service could be improved.

Surly rude flight attendants. I ordered the chicken and was given a vegetarian meal with no explanation and no opportunity to change it. I tried to order another beverage and was told by the young humorless flight attendant to “wait”. And she never came back. The seats were very uncomfortable and cramped. The last time I flew British Airways was many years ago but I remember it was amazing and the crew were very charming. This was a terrible disappointment given the cost of the flight.

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