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Cheap flights from London Heathrow Airport to Siem Reap, Cambodia from £384

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 7/7. Fares are subject to change and may not be available on all flights or dates of travel.
LHR — SAI
2 Aug — 9 Aug1
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 3 July 2026.

Thu 3/919:30
LHR
-
SAI
2 stops17h 25m
Multiple Airlines
Tue 29/909:40
SAI
-
LHR
2 stops18h 05m
Multiple Airlines
Deal found 28/6£587
Wed 2/913:50
LHR
-
SAI
2 stops23h 05m
SWISS
Thu 1/1009:40
SAI
-
LHR
2 stops28h 15m
SWISS
Deal found 28/6£590
Sat 31/1018:40
LHR
-
SAI
2 stops32h 10m
SWISS
Mon 9/1109:55
SAI
-
LHR
2 stops18h 45m
SWISS
Deal found 30/6£599
Wed 30/918:40
LHR
-
SAI
2 stops33h 00m
SWISS
Mon 5/1009:40
SAI
-
LHR
2 stops18h 05m
SWISS
Deal found 1/7£599
Wed 30/918:40
LHR
-
SAI
2 stops33h 00m
SWISS
Tue 27/1016:45
SAI
-
LHR
2 stops22h 20m
SWISS
Deal found 27/6£605
Tue 1/908:45
LHR
-
SAI
2 stops28h 10m
SWISS
Tue 29/909:40
SAI
-
LHR
2 stops31h 40m
SWISS
Deal found 28/6£605
Sat 31/1018:40
LHR
-
SAI
2 stops32h 10m
SWISS
Sat 7/1116:45
SAI
-
LHR
2 stops25h 30m
SWISS
Deal found 30/6£606
Fri 30/1018:40
LHR
-
SAI
2 stops32h 10m
SWISS
Sun 8/1109:55
SAI
-
LHR
2 stops18h 45m
SWISS
Deal found 30/6£614
Thu 1/1013:50
LHR
-
SAI
2 stops23h 05m
SWISS
Sun 11/1009:40
SAI
-
LHR
2 stops18h 05m
SWISS
Deal found 28/6£625
Thu 3/912:20
LHR
-
SAI
2 stops24h 35m
Multiple Airlines
Wed 30/909:40
SAI
-
LHR
2 stops18h 05m
Multiple Airlines
Deal found 28/6£627
Wed 2/912:10
LHR
-
SAI
2 stops24h 45m
SWISS
Wed 30/909:40
SAI
-
LHR
2 stops28h 15m
SWISS
Deal found 28/6£630
Thu 29/1013:45
LHR
-
SAI
2 stops22h 00m
SWISS
Mon 9/1109:55
SAI
-
LHR
2 stops32h 20m
SWISS
Deal found 30/6£631

Find flight deals from Heathrow to Siem Reap

Discover tips and strategies to find the most affordable flight options for your journey from Heathrow (LHR) to Siem Reap (SAI). Learn about various techniques such as flexible date searches, comparing prices across and setting up price alerts. Use these methods to find the cheapest flights available for your travel needs. Data last updated 3 July 2026.

Round-trip from

£587

One-way from

£384

Popular in

July

Cheapest in

March

Average price

£918
SWISS
  • SWISS
  • 3/9-29/9
  • 4 total stops
  • 35h 30m total
  • London to Siem Reap
Search Deals
Etihad Airways
  • Etihad Airways
  • 7/7
  • 2 total stops
  • 19h 45m 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. 1% potential price decrease (£8 potential savings vs. average return price).
Search Deals
Average for round-trip flights in July 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 3 July 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

Thu 29/10

09:00-18:45

2 stops26h 45m

Siem Reap–Angkor Intl

Sun 8/11

09:55-21:40

2 stops18h 45m

£646

LondonSiem Reap

LHR - SAI

LHRSAI

London Heathrow

Sat 7/11

18:40-09:50

2 stops32h 10m

Siem Reap–Angkor Intl

Sat 21/11

09:55-08:05

2 stops29h 10m

£678

LondonSiem Reap

LHR - SAI

LHRSAI

London Heathrow

Fri 25/9

16:50-21:30

2 stops22h 40m

Siem Reap–Angkor Intl

Tue 29/9

23:50-14:25

2 stops20h 35m

£811

LondonSiem Reap

LHR - SAI

LHRSAI

London Heathrow

Sun 30/8

20:45-09:00

2 stops30h 15m

Siem Reap–Angkor Intl

Fri 2/10

19:35-12:45

2 stops23h 10m

£846

LondonSiem Reap

LHR - SAI

LHRSAI

London Heathrow

Fri 4/9

21:45-09:00

2 stops29h 15m

Siem Reap–Angkor Intl

Tue 29/9

19:35-12:45

2 stops23h 10m

£846

LondonSiem Reap

LHR - SAI

LHRSAI

London Heathrow

Tue 1/9

21:45-09:00

2 stops29h 15m

Siem Reap–Angkor Intl

Sat 3/10

19:35-12:45

2 stops23h 10m

£846

LondonSiem Reap

LHR - SAI

LHRSAI

London Heathrow

Wed 2/9

20:45-09:00

2 stops30h 15m

Siem Reap–Angkor Intl

Wed 30/9

19:35-12:45

2 stops23h 10m

£848

LondonSiem Reap

LHR - SAI

LHRSAI

London Heathrow

Thu 19/11

22:00-21:10

2 stops40h 10m

Siem Reap–Angkor Intl

Sun 13/12

13:20-16:10

2 stops33h 50m

£858

LondonSiem Reap

LHR - SAI

LHRSAI

London Heathrow

Mon 10/8

16:50-21:30

2 stops22h 40m

Siem Reap–Angkor Intl

Fri 4/9

12:55-12:25

2 stops29h 30m

£939

LondonSiem Reap

LHR - SAI

LHRSAI

London Heathrow

Fri 4/9

09:25-09:40

1 stop18h 15m

Siem Reap–Angkor Intl

Sat 20/2

10:45-07:40

1 stop27h 55m

£953

Flights are sorted by cheapest return flights first.

Deals found on 29/6

Showing 1-10 of 18 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

What’s the top stopover airport for flights from London Heathrow Airport to Siem Reap?

Share of one-stop return flights from London Heathrow Airport to Siem Reap chosen by Cheapflights users in the past 12 months, using the same stopover each way.

Singapore (SIN) – chosen by Cheapflights users on 65% of one-stop itineraries from London Heathrow Airport to Siem Reap on Cheapflights.

What’s the cheapest stopover airport for flights from London Heathrow Airport to Siem Reap?

Average return fare for one-stop flights from London Heathrow Airport to Siem Reap, chosen by Cheapflights users in the past 12 months, with the same stopover each way.

Singapore (SIN) is the most affordable one-stop option, with an average return flight price of £789.

What’s the fastest stopover option from London Heathrow Airport to Siem Reap?

Shortest average travel time for one-stop one-way flights from London Heathrow Airport to Siem Reap, based on itineraries clicked by Cheapflights users over the past 12 months, grouped by stopover airport.

Flights via Bangkok (BKK) have the shortest average one-way travel time for one-stop routes: 13h 55m.

Which airport typically offers the quickest stopover for flights from London Heathrow Airport to Siem Reap?

Average stopover duration for one-stop one-way flights from London Heathrow Airport to Siem Reap, chosen by Cheapflights users in the last 12 months, grouped by stopover airport.

Flights via Ho Chi Minh City (SGN) offer the fastest connection on this route, with an average stopover time of 1h 53m.

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 3 July 2026.
Read reviews from past customers who have flown with Singapore Airlines,Thai Airways, andVietnam Airlines from London Heathrow Airport to Siem Reap. Users can see the overall rating for each airline as well as how each is rated in terms of entertainment options, comfort, food, crew/service, and boarding process.
Singapore Airlines
8.2
Very Good
1,557 reviews
Check prices

Entertainment

8.1

Boarding

8.3

Crew

8.6

Food

7.8

Comfort

8.0

Overall

8.2

Reviews

1 / 20
8.0
Excellent

Matt,Jun 2026

SIN - CMB

Crew were flat or busy but so awesome and polite. There was one guy, prob the senior crew member, looked and acted way too serious and too important to smile and say hello
Singapore Airlines
8.2
Very Good
1,557 reviews
Singapore Airlines
8.2
Very Good
1,557 reviews
Check prices

Entertainment

8.1

Boarding

8.3

Crew

8.6

Food

7.8

Comfort

8.0

Overall

8.2

Reviews

1 / 20
8.0
Excellent

Matt,Jun 2026

SIN - CMB

Crew were flat or busy but so awesome and polite. There was one guy, prob the senior crew member, looked and acted way too serious and too important to smile and say hello
Thai Airways
7.9
Good
409 reviews
Singapore Airlines
8.2
Very Good
1,557 reviews
Check prices

Entertainment

8.1

Boarding

8.3

Crew

8.6

Food

7.8

Comfort

8.0

Overall

8.2

Reviews

1 / 20
8.0
Excellent

Matt,Jun 2026

SIN - CMB

Crew were flat or busy but so awesome and polite. There was one guy, prob the senior crew member, looked and acted way too serious and too important to smile and say hello
Vietnam Airlines
7.7
Good
275 reviews
Singapore Airlines
8.2
Very Good
1,557 reviews
Check prices

Entertainment

8.1

Boarding

8.3

Crew

8.6

Food

7.8

Comfort

8.0

Overall

8.2

Reviews

1 / 20
8.0
Excellent

Matt,Jun 2026

SIN - CMB

Crew were flat or busy but so awesome and polite. There was one guy, prob the senior crew member, looked and acted way too serious and too important to smile and say hello
Austrian Airlines
7.6
Good
938 reviews
Singapore Airlines
8.2
Very Good
1,557 reviews
Check prices

Entertainment

8.1

Boarding

8.3

Crew

8.6

Food

7.8

Comfort

8.0

Overall

8.2

Reviews

1 / 20
8.0
Excellent

Matt,Jun 2026

SIN - CMB

Crew were flat or busy but so awesome and polite. There was one guy, prob the senior crew member, looked and acted way too serious and too important to smile and say hello

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.

  • What airport do you fly into for flights to Siem Reap from London Heathrow?

    For a flight from London Heathrow to Siem Reap, you will be flying into Siem Reap–Angkor Intl. Siem Reap–Angkor Intl (SAI) is just 24.7 mi from the center of the city. Siem Reap–Angkor Intl is the only Siem Reap airport and it handles 0 inbound flights from London Heathrow per day. 4 airlines have flights to Siem Reap–Angkor Intl from London Heathrow on a regular basis.

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

    A quick flight from London Heathrow Airport to Siem Reap can take about 22h 40m. SWISS provides one of the quickest options available for as low as £811. Airlines will cover a distance of 6106 mi. Both multi-stop and direct flights can be found to your destination and back.

  • What are the cheapest airlines flying from London Heathrow Airport to Siem Reap round-trip?

    Cheapflights users have booked flights from London Heathrow Airport to Siem Reap round-trip from £543. Other airlines that can offer you cheap pricing are Vietnam Airlines, from £621, and Singapore Airlines, from £669. These flights start at 33% lower than the current average price 3 months from now.

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

    The cheapet airlines for a one-way flight from London Heathrow Airport to Siem Reap are Vietnam Airlines (£455), Singapore Airlines (£519), and Thai Airways (£563).

  • 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.

See more FAQs

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Alternative routes for Heathrow to Siem Reap

See prices for flight routes from nearby airports that may be better suited for you.
Gatwick to Siem Reap flights
London City to Siem Reap flights
Stansted to Siem Reap flights
Luton to Siem Reap flights

Top 4 airlines flying from Heathrow to Siem Reap

Discover the top 4 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 3 July 2026.
AirlineCheapestAverageFlexibilityOn-time
Austrian AirlinesCheapest£543Average£690FlexibilityNo cancel feeOn-time78%
Search Austrian Airlines flights
Vietnam AirlinesCheapest£621Average£821FlexibilityNo cancel feeOn-time81%
Search Vietnam Airlines flights
Singapore AirlinesCheapest£669Average£789FlexibilityNo cancel feeOn-time81%
Search Singapore Airlines flights
Thai AirwaysCheapest£829Average£964FlexibilityNo 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?

When you search for this flight from Heathrow to Siem Reap, Cheapflights searches on 900+ travel sites to save you time finding great flight deals online. Additionally, we offer filter features so you can choose a preferred cabin class or airline, see different price ranges, and much more so you can book the flight for you.

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

It’s simple! Cheapflights, which is free to use for everyone, saves millions of users time and money every year by helping them find the cheapest and most suitable flights from Heathrow to Siem Reap.

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

Need flexible booking options for your flight to Siem Reap from Heathrow? Don’t worry, Cheapflights have you covered. Use our search filter to only show flights with no change fees.

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

Not ready to book yet? You can track prices for flights from Heathrow to Siem Reap on Cheapflights with our Price Alert feature and get notified when better prices are available.

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