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Cheap flights from London Heathrow Airport to Siem Reap from £335

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 7/6. Fares are subject to change and may not be available on all flights or dates of travel.
LHR — SAI
21 feb — 28 feb1
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 22 gennaio 2026.

ven 5/619:30
LHR
-
SAI
2 stops17h 15m
Multiple Airlines
ven 12/609:40
SAI
-
LHR
2 stops18h 05m
Multiple Airlines
Deal found 21/1£543
lun 16/321:00
LHR
-
SAI
2 stops29h 10m
Multiple Airlines
lun 30/321:10
SAI
-
LHR
2 stops27h 30m
Multiple Airlines
Deal found 21/1£561
lun 2/319:25
LHR
-
SAI
2 stops40h 15m
Multiple Airlines
mar 24/316:45
SAI
-
LHR
2 stops30h 35m
Multiple Airlines
Deal found 20/1£587
mar 17/221:25
LHR
-
SAI
1 stop29h 35m
Multiple Airlines
ven 3/421:10
SAI
-
LHR
2 stops27h 30m
Multiple Airlines
Deal found 20/1£619
gio 26/221:25
LHR
-
SAI
1 stop29h 35m
Malaysia Airlines
mar 24/311:00
SAI
-
LHR
1 stop35h 25m
Malaysia Airlines
Deal found 21/1£621
mar 7/421:35
LHR
-
SAI
1 stop30h 25m
Malaysia Airlines
mar 5/511:00
SAI
-
LHR
1 stop35h 35m
Malaysia Airlines
Deal found 21/1£633
dom 15/313:55
LHR
-
SAI
2 stops37h 55m
Multiple Airlines
dom 22/321:40
SAI
-
LHR
2 stops40h 00m
Multiple Airlines
Deal found 20/1£634
lun 16/321:00
LHR
-
SAI
3 stops65h 00m
China Eastern
lun 30/321:10
SAI
-
LHR
3 stops51h 30m
China Eastern
Deal found 21/1£657
dom 1/320:55
LHR
-
SAI
2 stops35h 25m
Multiple Airlines
lun 23/321:40
SAI
-
LHR
2 stops27h 30m
Multiple Airlines
Deal found 21/1£669
ven 5/622:05
LHR
-
SAI
1 stop29h 35m
Singapore Airlines
ven 12/616:00
SAI
-
LHR
1 stop33h 30m
Singapore Airlines
Deal found 21/1£686

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 22 gennaio 2026.

Round-trip from

£543

One-way from

£335

Popular in

December

Cheapest in

September

Average price

£730
SWISS
  • SWISS
  • 5/6-12/6
  • 4 total stops
  • 35h 20m total
  • London to Siem Reap
Search Deals
7/6
  • 7/6
  • 3 total stops
  • 45h 05m total
  • London to Siem Reap
Search Deals
Highest demand for flights based on searches. 7% potential increase in price (£52 potential increase over avg. return price).
Search Deals
Cheapest flight prices on average. 3% potential price decrease (£24 potential savings vs. average return price).
Search Deals
Average for round-trip flights in January 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 22 gennaio 2026.
Use the filters below to find and compare flights from London Heathrow Airport to Siem Reap that are best for you.

Fly from

Heathrow

Fly to

Siem Reap

Route

Depart

Return

Price

LondonSiem Reap

LHR - SAI

LHRSAI

London Heathrow

mar 17/2

21:25-10:00

1 stop29h 35m

Siem Reap–Angkor Intl

ven 3/4

21:10-18:40

2 stops27h 30m

£619

LondonSiem Reap

LHR - SAI

LHRSAI

London Heathrow

mar 7/4

21:35-10:00

1 stop30h 25m

Siem Reap–Angkor Intl

mar 5/5

11:00-16:35

1 stop35h 35m

£633

LondonSiem Reap

LHR - SAI

LHRSAI

London Heathrow

mar 7/4

21:35-10:00

1 stop30h 25m

Siem Reap–Angkor Intl

sab 9/5

11:00-16:35

1 stop35h 35m

£633

LondonSiem Reap

LHR - SAI

LHRSAI

London Heathrow

dom 15/3

13:55-10:50

2 stops37h 55m

Siem Reap–Angkor Intl

dom 22/3

21:40-06:40

2 stops40h 00m

£634

LondonSiem Reap

LHR - SAI

LHRSAI

London Heathrow

lun 2/3

06:00-15:00

3 stops26h 00m

Siem Reap–Angkor Intl

mar 24/3

11:45-16:20

2 stops35h 35m

£640

LondonSiem Reap

LHR - SAI

LHRSAI

London Heathrow

mar 17/2

21:00-21:00

3 stops41h 00m

Siem Reap–Angkor Intl

ven 3/4

21:10-18:40

2 stops27h 30m

£697

LondonSiem Reap

LHR - SAI

LHRSAI

London Heathrow

sab 14/3

18:40-18:45

2 stops41h 05m

Siem Reap–Angkor Intl

sab 28/3

22:00-17:40

2 stops26h 40m

£701

LondonSiem Reap

LHR - SAI

LHRSAI

London Heathrow

lun 2/3

09:10-15:55

1 stop23h 45m

Siem Reap–Angkor Intl

mar 24/3

10:45-05:55

1 stop26h 10m

£703

LondonSiem Reap

LHR - SAI

LHRSAI

London Heathrow

mar 3/2

21:00-21:00

3 stops41h 00m

Siem Reap–Angkor Intl

mar 24/2

22:00-17:30

2 stops26h 30m

£721

LondonSiem Reap

LHR - SAI

LHRSAI

London Heathrow

dom 5/4

21:35-10:00

1 stop30h 25m

Siem Reap–Angkor Intl

gio 7/5

11:00-16:35

1 stop35h 35m

£724

Flights are sorted by cheapest return flights first.

Deals found on 21/1

Showing 1-10 of 23 results
1
2
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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 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 £584). Flying from London Heathrow Airport to Region of Siem Reap in August is currently the most expensive (average of £894). 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 22 gennaio 2026.
Get a feel of what it's like to fly with Singapore Airlines, Thai Airways, andAustrian 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
8.1
Very Good
1,434 reviews
Check prices

Boarding

8.3

Entertainment

8.0

Crew

8.6

Overall

8.1

Comfort

8.0

Food

7.8

Reviews

1 / 20
10.0
Excellent

Juliet,Oct 2025

PUS - SIN

Very kind staff to arrange my luggage and really appreciate all help.
Singapore Airlines
8.1
Very Good
1,434 reviews
Singapore Airlines
8.1
Very Good
1,434 reviews
Check prices

Boarding

8.3

Entertainment

8.0

Crew

8.6

Overall

8.1

Comfort

8.0

Food

7.8

Reviews

1 / 20
10.0
Excellent

Juliet,Oct 2025

PUS - SIN

Very kind staff to arrange my luggage and really appreciate all help.
Thai Airways
7.8
Good
379 reviews
Singapore Airlines
8.1
Very Good
1,434 reviews
Check prices

Boarding

8.3

Entertainment

8.0

Crew

8.6

Overall

8.1

Comfort

8.0

Food

7.8

Reviews

1 / 20
10.0
Excellent

Juliet,Oct 2025

PUS - SIN

Very kind staff to arrange my luggage and really appreciate all help.
Austrian Airlines
7.6
Good
894 reviews
Singapore Airlines
8.1
Very Good
1,434 reviews
Check prices

Boarding

8.3

Entertainment

8.0

Crew

8.6

Overall

8.1

Comfort

8.0

Food

7.8

Reviews

1 / 20
10.0
Excellent

Juliet,Oct 2025

PUS - SIN

Very kind staff to arrange my luggage and really appreciate all help.
Vietnam Airlines
7.6
Good
221 reviews
Singapore Airlines
8.1
Very Good
1,434 reviews
Check prices

Boarding

8.3

Entertainment

8.0

Crew

8.6

Overall

8.1

Comfort

8.0

Food

7.8

Reviews

1 / 20
10.0
Excellent

Juliet,Oct 2025

PUS - SIN

Very kind staff to arrange my luggage and really appreciate all help.
Lufthansa
6.8
Okay
7,736 reviews
Singapore Airlines
8.1
Very Good
1,434 reviews
Check prices

Boarding

8.3

Entertainment

8.0

Crew

8.6

Overall

8.1

Comfort

8.0

Food

7.8

Reviews

1 / 20
10.0
Excellent

Juliet,Oct 2025

PUS - SIN

Very kind staff to arrange my luggage and really appreciate all help.

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 30h 25m. Malaysia Airlines provides one of the quickest options available for as low as £633. Airlines will cover a distance of 6106 mi.

  • 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 £584). Flying from London Heathrow Airport to Region of Siem Reap in August is currently the most expensive (average of £894). 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 22 gennaio 2026.
AirlineCheapestAverageFlexibilityOn-time
Austrian AirlinesCheapest£539Average£690FlexibilityNo cancel feeOn-time78%
Search Austrian Airlines flights
Vietnam AirlinesCheapest£615Average£718FlexibilityNo cancel feeOn-time81%
Search Vietnam Airlines flights
Singapore AirlinesCheapest£668Average£750FlexibilityNo cancel feeOn-time81%
Search Singapore Airlines flights
LufthansaCheapest£733Average£768FlexibilityNo cancel feeOn-time76%
Search Lufthansa flights
Thai AirwaysCheapest£859Average£947FlexibilityNo 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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