LHR - SAI

£371 Find Cheap Flights from London to Siem Reap

This is the cheapest one-way flight price found by a KAYAK user in the last 72 hours by searching for a flight from London to Siem Reap departing on 18/5. 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 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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41,299,237 searches in the past 7 days on KAYAK

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Everything you should know

Cheapest return fare
£577
Typical prices: £705-£663
Multiple Airlines
Wed 20/5Wed 27/5
LHR - SAI • 2 stops
Cheapest one-way flight
£371
Typical prices: £400-£462
Multiple Airlines
Mon 18/5
LHR - SAI • 2 stops
Top airlines
Cheapest • from £753 (return)
Best reviews • 8.2 score
Airline reviews
Airline reviews
+1
+1
Airline reviews
Airline reviews
+1
Direct flights
Not available
There are currently no direct flights between London and Siem Reap. You’ll need at least 1 connection.
Insights
Insights
Insights
Insights
Top stopover airports
Cheapest • Avg £755 (return)
Shortest trip • 13h 55m (one-way)
Insights
Insights
Insights
Insights
When to book
in advance
Our data shows that travellers who book at least 2 weeks in advance save around 33% compared to booking last minute.
Insights
Insights
Insights
Insights
When to travel
Cheapest • 18% price drop
Most popular
Good to know
Good to know
+1
+1
Good to know
Good to know
+1
Start a new search
KAYAK searches hundreds of sites at once to find you the best travel deals.
We hope you love your trip to Siem Reap!
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

Wed, 20 May - Wed, 27 May
Multiple Airlines Logo
16:15 - 18:45
LHR
-
SAI
20h 30m
2 stops
Multiple Airlines Logo
19:30 - 07:30
SAI
-
LHR
42h 00m
2 stops
£577Multiple Airlines
Mon, 18 May - Sun, 24 May
Multiple Airlines Logo
16:15 - 18:45
LHR
-
SAI
20h 30m
2 stops
Multiple Airlines Logo
09:45 - 07:30
SAI
-
LHR
27h 45m
2 stops
£582Multiple Airlines
Mon, 18 May - Sun, 24 May
Multiple Airlines Logo
20:45 - 11:10
LHR
-
SAI
32h 25m
3 stops
Multiple Airlines Logo
19:05 - 18:45
SAI
-
LHR
29h 40m
2 stops
£643Multiple Airlines
Tue, 12 May - Sun, 17 May
Multiple Airlines Logo
09:30 - 14:50
LHR
-
SAI
23h 20m
2 stops
Multiple Airlines Logo
10:00 - 07:00
SAI
-
LHR
27h 00m
2 stops
£665Multiple Airlines
Mon, 18 May - Sun, 24 May
Multiple Airlines Logo
20:45 - 11:10
LHR
-
SAI
32h 25m
3 stops
Multiple Airlines Logo
19:10 - 18:45
SAI
-
LHR
29h 35m
3 stops
£692Multiple Airlines
Thu, 30 Apr - Mon, 25 May
Multiple Airlines Logo
14:40 - 18:45
LHR
-
SAI
22h 05m
2 stops
Multiple Airlines Logo
19:30 - 12:40
SAI
-
LHR
23h 10m
2 stops
£708Multiple Airlines
Tue, 12 May - Sun, 17 May
Multiple Airlines Logo
06:30 - 14:50
LHR
-
SAI
26h 20m
3 stops
Multiple Airlines Logo
16:55 - 22:10
SAI
-
LHR
35h 15m
3 stops
£710Multiple Airlines
Tue, 12 May - Sun, 17 May
Multiple Airlines Logo
06:30 - 14:50
LHR
-
SAI
26h 20m
3 stops
Multiple Airlines Logo
10:00 - 15:05
SAI
-
LHR
35h 05m
2 stops
£714Multiple Airlines
Fri, 1 May - Wed, 27 May
Multiple Airlines Logo
16:15 - 18:45
LHR
-
SAI
20h 30m
2 stops
Multiple Airlines Logo
19:30 - 07:30
SAI
-
LHR
42h 00m
2 stops
£724Multiple Airlines
Fri, 10 Apr - Mon, 4 May
Multiple Airlines Logo
20:45 - 17:50
LHR
-
SAI
39h 05m
2 stops
Multiple Airlines Logo
15:10 - 07:00
SAI
-
LHR
45h 50m
2 stops
£727Multiple 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.

How much is a return flight from London Heathrow Airport to Siem Reap?

This analysis is based on the cheapest return trip price found on KAYAK in the last 12 months by searching for a flight from London Heathrow Airport to Siem Reap departing in May.

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 £670 (return) on average. On the other hand, the most expensive months are August and July, where the average cost of round-trip tickets is £1,201 and £889 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 2 weeks before departure, which saves you about 33% compared to booking last minute. For the absolute cheapest price, our data suggests you should book 3 weeks before departure.

Good to know - Cheap tickets from London to Siem Reap

Low seasonAugust
Cheapest flight£371
Best time to beat the crowds but there is an average 48% increase in price.
Most popular time to fly and prices are also 5% lower on average.
Flight from London to Siem Reap

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

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

    In the last 3 days, the lowest price for a flight from London Heathrow Airport to Siem Reap was £371 for a one-way ticket and £577 for a return.

  • Which airports will I be using when flying from London to Siem Reap?

    London and Siem Reap are both served by 1 main airport. You will leave London from London Heathrow and will be arriving at Siem Reap–Angkor Intl.

  • 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 £756 and an overall rating of 8.2, Singapore Airlines is the most popular choice. Thai Airways is also a great choice for the route, with an average price of £939 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.
8.2
Singapore AirlinesOverall score based on 1484 reviews
8.3Boarding
8.0Entertainment
7.8Food
8.0Comfort
8.6Crew
Airline reviews

I loved the full Taylor Swift selection but felt that the other selections were limited, didn’t span the popular music eras nor a wide enough range of music genres. BUT the seat and bed were GREAT (it was wide, long enough, had great storage, firm enough to uphold body postural comfort). Outstanding crew and really great food - gourmet innovative dim sum breakfast so different from the boring standard fare offered by many other business class products.

10.0 ExcellentEirene, Mar 2026
SIN - MEL
Read more Singapore Airlines reviews

I loved the full Taylor Swift selection but felt that the other selections were limited, didn’t span the popular music eras nor a wide enough range of music genres. BUT the seat and bed were GREAT (it was wide, long enough, had great storage, firm enough to uphold body postural comfort). Outstanding crew and really great food - gourmet innovative dim sum breakfast so different from the boring standard fare offered by many other business class products.

Crew is excellent Wifi needs to be improved in order to connect to the internet.

Service was very good, food and entertainment systems were good

First time flying with Singapore airlines and I’ll give them two thumbs up 👍 👍

Food was served to different people at different times and it wasn't clear why. The crew apologized for the wait. But it felt odd and inconsistent. They could use charging ports on each of the seats. Mine didn't have any. Also, they could've offered more snacks. It was a 12+ hour flight and no snacks were ever offered. Everything else was OK.

toilets could be cleaned more frequently, everything else was pretty good.

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.

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.

HAVING ANNOUNCEMENTS FOR PEOPLE TO BOARD ACCORDING TO GROUP IS ESSENTIAL N ENSURING N CUTTING OF QUEUES, EXCEPT FOR PRIORITY CLASS PASSENGERS ON A SEPARATE Q

We still get drinks and a snack. Love the gift bags too.

business class is old but still done very well by the team.

Excellent airline. The plane was clean and the staff were very attentive

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.

flight departure was late, with no updates on status of departure

The aircraft was little tired but the food and service was outstanding

It was ok, it felt more like an internal flight than an international flight so I guess expected a slightly better standard. Nothing really wrong with it but there was no inflight entertainment. Food and service was good.

This was our fourth domestic flight with Vietnam Airlines, and once again we found the experience very suitable. Check-in was easy and efficient. They did take our carry-on luggage, but that was fine. I’m actually happy not to deal with it on such a short flight. The flight was just over an hour, departed on time, and we climbed above the clouds into a beautiful sunset. Even on such a short flight, they served water, which we appreciated. Luggage came out into carousel in Nha Trang in good time and off we went to meet our GRAB. Also, Vietnam Airlines have easy to locate ground level offices in cities and towns where you can get assistance with staff. I liked this service as we did go visit one in Nha Trang. We would definitely recommend Vietnam Airlines and wouldn’t hesitate to fly with them again.

Really good 👍 This was our first time flying with Vietnam Airlines. It was a short domestic flight, so no meal service, but boarding was organized and the flight departed and arrived on schedule. The flight attendants were professional and neatly presented. All in all, a very good first experience. We would recommend Vietnam Airlines.

We flew with their partner VESCO on a small plane, it was a really good flight. There was no food or entertainment as it’s a one hour hopper flight.

The flight boarded and departed pretty much on time as it’s just a one hour flight there is no food or entertainment so I marked that at the neutral but they do offer water and I’m sure if you needed some food you could bring your own onboard. This was our third internal flight with Vietnam Airways and I recommend them.

This is a very short commuter flight, so there is no food or flight entertainment. Hence, I marked it in the neutral flight left on time. The plane was full pretty much and it was a pretty easy flight overall very good.

The flight crew and attendants are very professional and polite.

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

Booked economy. Seat felt like it was a bit more roomy than my last trans Atlantic flights. I had a nice person sitting next to me. Everything was as good as it could be considering you are 35,000 feet up in the air and in a metal container. Beers, wine, food were all readily available. Plenty of movies and shows to watch. Friendly flight staff

Short flight. Bare bones and kinda seeming like an older plane. But got me there on time and that's what counts. Perfectly fine flight all the way from start to finish.

My Austrian Air flight from Montenegro to Vienna was delayed by three hours because their plane de-icer was broken and they had to wait for the sun to come up before the ice could melt. This meant we missed our United flight altogether. So I can't speak about United, but I was not impressed by Austrian Air. They made us check in two carry on bags for a 60% full flight, and the bags didn't find us in the US for ten days. The re-routing they arranged included an extra leg, a midnight taxi ride across New Jersey and New York, and a five hour sleep in a hotel. Not impressed.

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.

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.

Very limited legroom in a 10 hour flight.very old plane.

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.

Flight map did not work. Crew was great, food was good, plane took off on time and landed early. That's all I can ask.

Missed it by a couple minutes and couldn’t find an alternative flight so had to spend the night in DC and after much shuffling from 1 airline to another managed to get a United to Frankfurt.

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.

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

Bought a seat in a flight that got changed out so ended up paying for a seat I would have had if I hadn't paid.

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 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.

Great experience, flight was on time and reached on destination on time .. very accurate and smooth experience

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

Information on your arrival and departure airports