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Cheap flights from London Heathrow Airport to Siem Reap from £394

This is the cheapest one-way flight price found by a Cheapflights user in the last 72 hours by searching for a flight departing on 17/5. Fares are subject to change and may not be available on all flights or dates of travel.
LHR — SAI
4 Jun — 11 Jun1
1 adult
1 adult, Economy, 0 bags

Cheap flight deals from Heathrow to Siem Reap

Enter your travel dates to find the best prices.

Cheapest flights from Heathrow to Siem Reap
Explore the most affordable flight options available from Heathrow to Siem Reap. Find the lowest fares from popular airlines and budget airlines, with prices last updated on 5 May 2026.

Fri 8/521:45
LHR
-
SAI
2 stops29h 15m
Etihad Airways
Sun 12/719:20
SAI
-
LHR
2 stops29h 25m
Etihad Airways
Deal found 2/5£585
Fri 12/621:45
LHR
-
SAI
2 stops29h 15m
Etihad Airways
Thu 25/615:10
SAI
-
LHR
2 stops21h 50m
Etihad Airways
Deal found 1/5£586
Thu 7/509:30
LHR
-
SAI
2 stops19h 45m
Etihad Airways
Thu 28/519:20
SAI
-
LHR
2 stops29h 25m
Etihad Airways
Deal found 5/5£592
Thu 28/509:30
LHR
-
SAI
2 stops19h 45m
Etihad Airways
Thu 18/615:10
SAI
-
LHR
2 stops21h 50m
Etihad Airways
Deal found 4/5£593
Fri 19/621:45
LHR
-
SAI
2 stops29h 15m
Etihad Airways
Fri 26/615:10
SAI
-
LHR
2 stops45h 50m
Etihad Airways
Deal found 5/5£594
Tue 25/818:40
LHR
-
SAI
2 stops42h 15m
SWISS
Tue 22/909:40
SAI
-
LHR
2 stops36h 45m
SWISS
Deal found 3/5£609
Sun 10/509:30
LHR
-
SAI
2 stops22h 50m
Etihad Airways
Sat 16/515:10
SAI
-
LHR
2 stops33h 35m
Etihad Airways
Deal found 5/5£616

Find flight deals from Heathrow to Siem Reap

Keep the following information in mind while searching for Heathrow to Siem Reap flight deals. Data was last updated 5 May 2026.

Round-trip from

£586

One-way from

£394

Popular in

December

Cheapest in

September

Average price

£741
Etihad Airways
  • Etihad Airways
  • 12/6-25/6
  • 4 total stops
  • 51h 05m total
  • London to Siem Reap
Search Deals
Etihad Airways
  • Etihad Airways
  • 17/5
  • 2 total stops
  • 22h 50m total
  • London to Siem Reap
Search Deals
Highest demand for flights based on searches. 7% potential increase in price (£47 potential increase over avg. return price).
Search Deals
Cheapest flight prices on average. 4% potential price decrease (£24 potential savings vs. average return price).
Search Deals
Average for round-trip flights in May 2026
Search Deals

Cheapflights Fare Finder

 
Customise your flight search to find flights from Heathrow to Siem Reap that fit within your specific budget. Explore options based on user searches and filter the results based on your desired price range. Find flights that match your budget for a cost-effective journey. Over the last 7 days, Cheapflights users made 858,174 searches. Data last updated 5 May 2026.
Use the filters below to find and compare flights from London Heathrow Airport to Siem Reap that are best for you.

Fly from

Fly to

Route

Depart

Return

Price

Cheapest return flight

LondonSiem Reap

LHR - SAI

LHRSAI

London Heathrow

Sun 1/11

21:00-21:00

2 stops41h 00m

Siem Reap–Angkor Intl

Sat 12/12

22:00-17:30

2 stops50h 30m

£745

LondonSiem Reap

LHR - SAI

LHRSAI

London Heathrow

Fri 30/10

15:50-21:10

2 stops22h 20m

Siem Reap–Angkor Intl

Tue 15/12

23:50-18:20

2 stops25h 30m

£781

LondonSiem Reap

LHR - SAI

LHRSAI

London Heathrow

Fri 25/9

14:25-21:30

2 stops25h 05m

Siem Reap–Angkor Intl

Tue 29/9

23:50-14:25

2 stops20h 35m

£818

LondonSiem Reap

LHR - SAI

LHRSAI

London Heathrow

Tue 27/10

21:00-21:00

2 stops41h 00m

Siem Reap–Angkor Intl

Fri 30/10

18:40-07:15

1 stop19h 35m

£897

LondonSiem Reap

LHR - SAI

LHRSAI

London Heathrow

Sat 31/10

11:00-17:40

1 stop23h 40m

Siem Reap–Angkor Intl

Fri 11/12

18:40-07:15

1 stop19h 35m

£947

LondonSiem Reap

LHR - SAI

LHRSAI

London Heathrow

Sat 31/10

11:00-17:40

1 stop23h 40m

Siem Reap–Angkor Intl

Sat 12/12

17:05-07:15

2 stops21h 10m

£954

LondonSiem Reap

LHR - SAI

LHRSAI

London Heathrow

Fri 30/10

06:20-17:40

2 stops28h 20m

Siem Reap–Angkor Intl

Sun 13/12

17:55-07:15

1 stop20h 20m

£958

LondonSiem Reap

LHR - SAI

LHRSAI

London Heathrow

Fri 30/10

11:00-19:40

1 stop25h 40m

Siem Reap–Angkor Intl

Mon 14/12

18:40-07:15

1 stop19h 35m

£992

LondonSiem Reap

LHR - SAI

LHRSAI

London Heathrow

Wed 29/7

21:45-16:55

2 stops37h 10m

Siem Reap–Angkor Intl

Mon 17/8

09:40-18:45

2 stops39h 05m

£1,039
Fastest return journey

LondonSiem Reap

LHR - SAI

LHRSAI

London Heathrow

Thu 28/5

18:55-18:20

1 stop17h 25m

Siem Reap–Angkor Intl

Thu 18/6

19:10-10:30

2 stops21h 20m

£1,091

Flights are sorted by cheapest return flights first.

Deals found on 5/5

Showing 1-10 of 20 resultsSorted by cheapest first
1
2

Best time to book a flight from Heathrow to Siem Reap

Have a flexible travel schedule? Discover the best time to fly to Siem Reap from Heathrow with our price prediction graph.
Estimated return price
Rates are based on past data. Find the cheapest month and day to book your flight based on your travel requirements, then search for cheap deals.

Cheapflights Insights

Everything you need to know about your flight from London Heathrow Airport to Siem Reap

How far ahead should I book a flight from London Heathrow Airport to Region of Siem Reap?

To ensure you get the cheapest price possible for a flight from London Heathrow Airport to Region of Siem Reap, you should look to book at least 53 days in advance of your intended travel date. The price of your flight may increase if you delay and leave booking until a week or so before departure.

What is the cheapest month to book a flight from London Heathrow Airport to Region of Siem Reap?

Currently, March is the cheapest month in which you can book a flight from London Heathrow Airport to Region of Siem Reap (average of £535). Flying from London Heathrow Airport to Region of Siem Reap in August is currently the most expensive (average of £1,017). There are several factors that can impact the price of a flight, so comparing airlines, departure airports and flight times can provide users with more options.

How much does it cost for a return flight from London Heathrow Airport to Region of Siem Reap?

Reviews of airlines servicing Siem Reap

Get insights into the airlines that provide service to Siem Reap. Read reviews, discover amenities, and learn about the overall travel experience offered by airlines. Use this information to make informed decisions when choosing an airline for your flight to Siem Reap. Reviews last updated 5 May 2026.
Get a feel of what it's like to fly with Singapore Airlines,Thai Airways, andVietnam Airlines from London Heathrow Airport to Siem Reap by reading reviews from past customers. You can also see how each airline compares in terms of entertainment options, comfort, food, crew/service, and boarding process.
Singapore Airlines
8.2
Very Good
1,509 reviews
Check prices

Crew

8.6

Comfort

8.0

Entertainment

8.0

Overall

8.2

Boarding

8.3

Food

7.8

Reviews

1 / 20
6.0
Good

Anonymous,Feb 2026

SAI - SIN

The only issue we had was seat selection. Was not easy to change, after they assigned seats. Also, the premium economy seats, are nothing special.. All and all safe flight with minor back issues.
Singapore Airlines
8.2
Very Good
1,509 reviews
Singapore Airlines
8.2
Very Good
1,509 reviews
Check prices

Crew

8.6

Comfort

8.0

Entertainment

8.0

Overall

8.2

Boarding

8.3

Food

7.8

Reviews

1 / 20
6.0
Good

Anonymous,Feb 2026

SAI - SIN

The only issue we had was seat selection. Was not easy to change, after they assigned seats. Also, the premium economy seats, are nothing special.. All and all safe flight with minor back issues.
Thai Airways
7.9
Good
401 reviews
Singapore Airlines
8.2
Very Good
1,509 reviews
Check prices

Crew

8.6

Comfort

8.0

Entertainment

8.0

Overall

8.2

Boarding

8.3

Food

7.8

Reviews

1 / 20
6.0
Good

Anonymous,Feb 2026

SAI - SIN

The only issue we had was seat selection. Was not easy to change, after they assigned seats. Also, the premium economy seats, are nothing special.. All and all safe flight with minor back issues.
Vietnam Airlines
7.7
Good
266 reviews
Singapore Airlines
8.2
Very Good
1,509 reviews
Check prices

Crew

8.6

Comfort

8.0

Entertainment

8.0

Overall

8.2

Boarding

8.3

Food

7.8

Reviews

1 / 20
6.0
Good

Anonymous,Feb 2026

SAI - SIN

The only issue we had was seat selection. Was not easy to change, after they assigned seats. Also, the premium economy seats, are nothing special.. All and all safe flight with minor back issues.
Austrian Airlines
7.6
Good
914 reviews
Singapore Airlines
8.2
Very Good
1,509 reviews
Check prices

Crew

8.6

Comfort

8.0

Entertainment

8.0

Overall

8.2

Boarding

8.3

Food

7.8

Reviews

1 / 20
6.0
Good

Anonymous,Feb 2026

SAI - SIN

The only issue we had was seat selection. Was not easy to change, after they assigned seats. Also, the premium economy seats, are nothing special.. All and all safe flight with minor back issues.
Lufthansa
6.8
Okay
7,974 reviews
Singapore Airlines
8.2
Very Good
1,509 reviews
Check prices

Crew

8.6

Comfort

8.0

Entertainment

8.0

Overall

8.2

Boarding

8.3

Food

7.8

Reviews

1 / 20
6.0
Good

Anonymous,Feb 2026

SAI - SIN

The only issue we had was seat selection. Was not easy to change, after they assigned seats. Also, the premium economy seats, are nothing special.. All and all safe flight with minor back issues.

Related info for your journey

Find useful and relevant information for your journey from Heathrow to Siem Reap. Access travel guides, tips, and recommendations to enhance your travel experience. Get information about local attractions, weather, transportation options, and more.

  • How long is the flight from London Heathrow Airport to Region of Siem Reap?

    A quick flight from London Heathrow Airport to Region of Siem Reap can take about 25h 05m. China Eastern provides one of the quickest options available for as low as £818. Airlines will cover a distance of 6106 mi. When browsing for deals, the options you’ll see will be for both direct flights and flights with stops.

  • What are the cheapest airlines to fly from London Heathrow Airport to Region of Siem Reap one-way?

    £448 is the cheapest one-way deal found within the past few days, from Vietnam Airlines. You may also be able to find cheap deals on Singapore Airlines and Thai Airways, with prices starting from £511 and £554, respectively.

  • Can I find deals for flights from Heathrow to Siem Reap that include hotel bookings?

    Yes. In addition to deals on Heathrow to Siem Reap flights, Cheapflights offers holiday packages that include both flights and hotel.

  • How can I find direct flights from Heathrow to Siem Reap?

    After entering your origin and destination, apply the non-stop filter on the search result page to find direct flights from Heathrow to Siem Reap.

  • Can I find deals for business class flights from Heathrow to Siem Reap?

    Yes. Cheapflights offers flight deals from Heathrow to Siem Reap by cabin class. In addition to browsing deals, you can also filter by cabin class on the search results page after making a search.

  • What is the cheapest month to book a flight from London Heathrow Airport to Region of Siem Reap?

    Currently, March is the cheapest month in which you can book a flight from London Heathrow Airport to Region of Siem Reap (average of £535). Flying from London Heathrow Airport to Region of Siem Reap in August is currently the most expensive (average of £1,017). There are several factors that can impact the price of a flight, so comparing airlines, departure airports and flight times can provide users with more options.

See more FAQs

Browse thousands of different options on Cheapflights for your next trip

Toggle through the tabs below to find thousands of options on Cheapflights for your next trip.

Top 5 airlines flying from Heathrow to Siem Reap

Discover the top 5 airlines that operate flights from Heathrow to Siem Reap. Compare their services, reliability, and customer satisfaction ratings to choose the airline that best suits your travel preferences and needs. Over the last 7 days, Cheapflights users made 858,174 searches. Data last updated 5 May 2026.
AirlineCheapestAverageFlexibilityOn-time
Austrian AirlinesCheapest£535Average£682FlexibilityNo cancel feeOn-time78%
Search Austrian Airlines flights
LufthansaCheapest£593Average£762FlexibilityNo cancel feeOn-time76%
Search Lufthansa flights
Vietnam AirlinesCheapest£614Average£808FlexibilityNo cancel feeOn-time81%
Search Vietnam Airlines flights
Singapore AirlinesCheapest£659Average£754FlexibilityNo cancel feeOn-time81%
Search Singapore Airlines flights
Thai AirwaysCheapest£856Average£936FlexibilityNo cancel feeOn-time77%
Search Thai Airways flights

Fly with Cheapflights

Find the best flight deals on Cheapflights, where travellers can enjoy low prices and a wide availability of flights to their desired destinations.

How does Cheapflights help users find flights from Heathrow to Siem Reap?

Cheapflights goes through 900+ travel sites to look for the best flight deals for flights from Heathrow to Siem Reap. Too many options? Cheapflights also provides filters for things like airlines, price ranges, and number of stops to help you make a decision easily.

Why should you use Cheapflights to find cheap flight tickets from Heathrow to Siem Reap?

Cheapflights helps you find that perfect flight to Siem Reap from Heathrow by searching from hundreds of airlines and agencies you know and love. We are also free to use, in case you were wondering!

Can Cheapflights find flights from Heathrow to Siem Reap with no change fees?

Certainly. Search results for flights to Siem Reap from Heathrow shown to you on Cheapflights can be narrowed down with different useful search filters, which includes flexible booking options.

Can Cheapflights notify me if prices for flights from Heathrow to Siem Reap become cheaper?

Yes, Cheapflights offers price alerts on Heathrow to Siem Reap flights so you can book your travel at the perfect time. Price Alerts can be enabled by clicking the bell icon next to the flight deals above and providing your email address where you want to receive the alerts.

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