LHR - SAI

Find Cheap Flights from London to Siem Reap

1 adult
1 adult, Economy, 0 bags

KAYAK searches hundreds of travel sites at once for deals on flights to Siem Reap

 
These are the airlines KAYAK users have selected most often from within our search results in flight searches from London to Siem Reap, as well as popular online travel agencies
These are the airlines KAYAK users have selected most often from within our search results in flight searches from London to Siem Reap, as well as popular online travel agencies
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Everything you should know

Cheapest return fare
Multiple Airlines
Thu 18/12
LHR - SAI • multi-stop
Cheapest one-way flight
Multiple Airlines
Thu 18/12
LHR - SAI • multi-stop
When to travel
May
Cheapest • 17% price drop
March
Most popular
Good to know
Good to know
+1
+1
Good to know
Good to know
+1
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Flight Deals
Booking Insights
Flight Deals

Cheap Flights from London to Siem Reap (LHR-SAI)

 
Here are some of the best deals found on KAYAK recently from the most popular airlines for return flights from London to Siem Reap 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 return flight deals from London to Siem Reap

Multiple Airlines Logo
LHR
-
SAI
6106 mimulti-stop
Multiple Airlines Logo
SAI
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LHR
6106 mimulti-stop
Multiple Airlines
Booking Insights

KAYAK's insights & trends for London to Siem Reap flights

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

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

To calculate monthly average prices, KAYAK takes all prices for each month over the last year for round-trip flights from London Heathrow Airport to Siem Reap, 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 London Heathrow Airport to Siem Reap is May, where tickets cost £664 (return) on average. On the other hand, the most expensive months are August and July, where the average cost of round-trip tickets is £1,151 and £882 respectively.

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

To calculate weekly average prices, KAYAK takes all prices for each week before departure over the last year for round-trip flights from London Heathrow Airport to Siem Reap, 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 London Heathrow Airport to Siem Reap, you should book around 1 week before departure. For the absolute cheapest price, our data suggests you should book 12 weeks before departure.

Good to know - Cheap tickets from London to Siem Reap

Low seasonJuly
Best time to beat the crowds but there is an average 10% increase in price.
Most popular time to fly and prices are also 3% lower on average.

When to book flights from London to Siem Reap

Are your dates flexible? Find out the best times to travel from London to Siem Reap based on our flight data from the last year. Discover the cheapest month and even day to fly.
Estimated return price
KAYAK looks at all historical flight data for each date to provide a predicted price for one-way trips or returns 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 London to Siem Reap flights

  • Which aircraft models fly most regularly from London to Siem Reap?

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

  • Which airline alliances offer flights from London to Siem Reap?

    SkyTeam, and Star Alliance are the airline alliances operating flights between London and Siem Reap, with SkyTeam being the most commonly used for this route.

  • Which is the best airline for flights from London to Siem Reap, Singapore Airlines or Thai Airways?

    The two airlines most popular with KAYAK users for flights from London to Siem Reap are Singapore Airlines and Thai Airways. With an average price for the route of £748 and an overall rating of 8.1, Singapore Airlines is the most popular choice. Thai Airways is also a great choice for the route, with an average price of £918 and an overall rating of 7.8.

  • How does KAYAK find such low prices on flights from London to Siem Reap?

    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 London to Siem Reap.

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

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

  • What is the Hacker Fare option on flights from London to Siem Reap?

    Hacker Fares allow you to combine one-way tickets in order to save you money over a traditional return ticket. You could then fly to Siem Reap with an airline and back to London with another airline.

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

    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 Siem Reap from London 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 flying from London to Siem Reap

 
See real verified KAYAK customer reviews for airlines flying from London to Siem Reap. 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 London to Siem Reap? 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.
8.1
Singapore AirlinesOverall score based on 1414 reviews
8.3Boarding
8.0Entertainment
8.0Comfort
8.6Crew
7.8Food
Airline reviews

Pleasant business class flight experience with good onboarding experience. Flight service team was excellent with usual book-the-chef menu available

8.0 ExcellentWee Keng, Nov 2025
ICN - SIN
Read more Singapore Airlines reviews

Pleasant business class flight experience with good onboarding experience. Flight service team was excellent with usual book-the-chef menu available

a completely full flight - felt quite carmped in, despite being on the window seat. Meal served could better. Surely different from pre-covid trips I used to take to and from Bangkok.

Wish the underseat compartment don’t have a restriction, can fit a personal item such as backpack fully like most Boeing

The business class seats were very uncomfortable. When in lie flat position my legs were very restricted.

Lounge a access was excellent as was the attentiveness and service from the crew as always. The food and drink supplied were of good quality. The entertainment system had a good selection and I liked the mapping system supplied. However the screen wild have been bigger and the operation a little smoother to navigate. The seats were barely comfortable, but adequate.

The staff on the plane were attentive and friendly. The frustration with the cabin crew was that we were served second to special diet people. And, we were in economy section. The boarding staff was mediocre. Got scolded for requesting to sit with spouse on 14 hours long flight home. Was told they cannot break up families for us. Didn’t understand how we were denied sitting together as we are husband and wife. After many words of exchange, we were accommodated. Cleaning crew did a horrible job! Bathrooms were unsanitary or dirty from beginning of flight! Didn’t expect sparkling as its economy, but did except decent.

Crew and service excellent. 2 hour delay for takeoff. SQ app showed flight on time.

The usual excellent experience with Singapore Airlines. The airplane was on time and actually early to Haneda Airport. The onboarding experience was pleasant with no delays, perhaps owing to the fact that the flight was not full. Nevertheless, the air crew were their usual outstanding standards in serving the passengers.

Very good flight from Boarding to landing -efficient and comfortable with decent entertainment options

Excelent service and plenty of food and drinks during the flight. Flight crew very attentive to our needs. Leg room between rows are very disappointing.

Good experience although the boarding gate is at the terminal extension hence need to leave lounge to head over earlier.

Thai Royal First is very good. Easy check in , Private room in the first class lounge and escort from ticketing to the plane. Once on board crew was very polite, food was outstanding, and the ride was smooth as silk. Restrooms were especially clean. Great Experience

I'm not interested in improving the airline. Therefore, I won't explain this in more detail. Next time I'll try a different one.

The flight (boarding) was delayed by 40-50 minutes and there was very crowed. They need to improve on the timeliness & boarding process. (They asked passenger to board in groups, but the 2nd group was standing there waiting for 20 minutes!). However, services from the crew was very good, also the food was good as well. I also found the legroom was quite comfortable.

Need to improve on punctuality. My flight was delayed by 1 hour.

Seats were uncomfortable and the vegetarian meal was awful. Some of the entertainment didn't work.

Except that our flight was cancelled, by mail, and later moved to 12 hours prior, then the experience was good. In Bangkok we were offered a hotel, it was fine, but would have been nice to know in advance😉

The flight was mostly fine, but I really wished that seats had an outlet to charge devices considering the length of the flight (15 hours there and 14 hours back).

Although booked meal of fruit only The crew had not received this special meal The same happened on my flight Bangkok / CAN The films are so old that best is to use own computer to watch downloads . Serve nuts but they do not warm up . Service is attentive , WC clean

Terrible. It’s like they are stuck in the dark ages. I brought a standard carry on suitcase and a back pack - I was told I could only carry on 7kg per bag - in business class, I was forced to remove articles from the suitcase and put them into my backpack! That’s the most ridiculous thing I’ve ever encountered in all my years of flying. The two bags weighed the same amount but one could not be more than 7kg. Holy cow.

Most of the crew members were rude, flight arrived late and we missed our connecting flight, they damaged my friends suitcase so badly that two wheels had been destroyed.

Excellent flight. The crew was exceptionally attentive and organized. Attention to details is unmatched.

Loved the courtesy and punctuality. Very professional and most importantly on time.

Great! They got my vegetarian meal right, flight was comfortable, they helped store my heavy luggage. Pleasant crew and flight staff.

I did wish they would give us the entire little bottle Bailey's instead of just have 1/2 bottle at a time

My layover in Vienna was supposed to be 35 minutes but because my flight was canceled I had to wait in the airport for an additional 8 hours.

The flight was delayed for 30 minutes with no apparent reason. There is no entertainment at all, and no USB or electric outlets for charging your phone or tablet.

Accessibility serious problems in Viena airport making it seriousely difficult in in-between gates and boarding travel. Pretens of breakfast and service care in the economy pathetic.

One thing I really liked about Austrian Airlines was that the flight attendants were very kind, and the in-flight entertainment offered many choices. One thing that could be improved is the meal service, since only a vegetarian option was offered — it would be better to have at least two choices

Despite the booked seats in front of the land we were moved to the back of the plane even first like 8 lines were totally without pasangers. When I tried to sit on empty seat flight attendant asked me to go to my dedicated seat in the fully crowded back of the plane. She was not able to explain why. Food was very poor on flight LAX - VIE.

Food and welcome services were good , however we experienced issues with the entertainment system and poor headsets

Very good flight and very kind crew Only thing is I wish there would be a vegetarian option for the meals

Lovely staff, comfortable seats. Transit time was short but they had great processes in place to get us on the plane.

For a domestic flight, seats are ok, but fir us as tall dutchies, the legroom is too small. However, for a short and affordable flight, is not a big problem. Staff is still very nice and a complementary water very welcome.

2 hours delay, time changes started already 2 days before the flight

Average, not more then that. Cannot compete with Singapore Airlines

I bought the front row seat and made and early online check in but they changed my seat to the back row without prior notice. The inflight meal was too poor, only a piece of small finger food. The boarding is a disaster, everyone is stuffed in a bus in chaos. Doesnt worth the money at all.

Poor. Flight was delay without prior notice. Poor boarding. Poor meal service. Plane was dirty and smelly. Does not worth the money.

Overall very nice airline. The seats were cloth unlike leather seats I am accustom to on planes. The food was adequate. I had to use a paper boarding pass as they do not like electronic boarding passes. I scanned my electronic pass, but the gate agent requested the paper pass. Luckily I had a paper pass, although my electronic pass worked and when the paper pass was scanned it stated I was already on board.

I am a bit upset with the check in counter, I signed up a wheelchair for my mom so they wouldn’t grant us her boarding pass. We got to the airport a couple of hours earlier and they had us wait and no one ever gave us her boarding pass or the wheelchair, I had to go back and complain when it was already time for our flight to board. Since we got their earlier, I could have easily pushed my mom myself and we could have relaxed and went to the lounge while waiting… when I finally got someone to help us he couldn’t explain how and why they dismissed us in the first place.

Crew was outstanding, helpful and friendly. Food is deteriorating. The snack at the end of the flight was not good, a greasy moosh of toast cheese snd other unidentifiable ingredients. Coming from Germany a pretzl with butter would have been better. Entertainment had a great selection.

Paid for exit row at the back of the plane. Window seat with lots of leg space. Food was inedible (as usual). Brought my own.

Boarding procedure should have the crew and personnel who are more trained, in a sense of precisely knowing what can be done and what cannot. They do not have the exact information on what you should do in the first place, also the boarding itself was slightly delayed due to the aircraft "not being ready".

Business Class was very comfortable and the food and service was top notch.

Efficiency of staff, and comfort and cleanliness of aircraft was all great. Maybe a hot drink without payment at that time in the morning would be good!

The food that was served was superb!!! Awesome snacks!!! Frequent drink service!!! To me, this was shocking. I took a British Airways flight from Denver to London for the first leg of my trip and the food was horrendous. Thank you for keeping us fed and satiated on such a long flight!!!!

The plane was late (as was my flight out from Birmingham the day before)

Not bad. We had preboarding tickets but the preboarding was badly managed. We lined up behind all the parents with little kids etc and when we got to the front of the line the attendant deliberately turned away from us and ignored us until I asked to be allowed to go to the gate. She started telling us that we had to wait until I told her we had preboarding then she let us through.

Cheapest airlines I have ever been on. I got downgraded and never got on united. I got rerouted through Vancouver onto jetwesf

The crew was the best I’ve ever encountered. Business class was spacious, immaculate, and very modern.

Everything you need to know for your flight from London to Siem Reap

Information on your arrival and departure airports