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 40m. Vietnam Airlines provides one of the quickest options available for as low as £782. 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?

£376 is the cheapest one-way deal found within the past few days, from Austrian Airlines. You may also be able to find cheap deals on Vietnam Airlines and Singapore Airlines, with prices starting from £448 and £500, respectively.

In terms of precipitation, rainfall in Region of Siem Reap ranges from 0.0 - 260.0 inches per month. September is typically the wettest month, when rainfall can reach 260.0 mm. January is typically the driest time to visit Region of Siem Reap when rainfall is around 0.0 mm.

If weather is an important factor for your trip to Region of Siem Reap, use this chart to help with planning. For those seeking warmer temperatures, April is the ideal time of year to visit, when temperatures reach an average of 29.0 C. Travellers hoping to avoid the cold should look outside of December, when temperatures are typically at their lowest (around 24.0 C).

What are the most popular airlines that fly from London Heathrow Airport to Region of Siem Reap?

The most popular airlines flying from London Heathrow Airport to Region of Siem Reap are Vietnam Airlines, Singapore Airlines and Thai Airways. Something to consider prior to booking your flight.

What is the cheapest time of day to fly from LHR to SI?

When flying from London Heathrow Airport to Region of Siem Reap, the time of day you decide to fly out makes little to no difference towards the overall price you’ll pay on tickets.

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.

£340+ Cheap Flights from London Heathrow Airport to Siem Reap

Cheap flight deals from Heathrow to Siem Reap

Enter your travel dates to find the best prices.

Cheapest

Best

Last-minute

One-way

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 1 September 2026.

Thu 3/1206:00 -

2 stops29h 45m

Mon 14/1209:55 -

2 stops35h 10m

Deal found 31/8£612

Mon 28/918:55 -

1 stop16h 15m

Mon 25/121:30 -

1 stop16h 45m

Deal found 30/8£625

Sun 8/1106:00 -

2 stops29h 45m

Wed 27/116:50 -

2 stops25h 25m

Deal found 29/8£626

Mon 30/1106:00 -

2 stops29h 45m

Sun 13/1209:55 -

2 stops18h 45m

Deal found 28/8£635

Sun 27/919:50 -

1 stop15h 20m

Wed 27/118:40 -

1 stop19h 35m

Deal found 30/8£638

Tue 10/1119:25 -

2 stops40h 20m

Sat 5/1209:55 -

2 stops29h 25m

Deal found 31/8£640

Wed 30/906:00 -

2 stops30h 55m

Wed 7/1019:35 -

2 stops18h 45m

Deal found 31/8£652

Tue 1/1219:25 -

2 stops16h 20m

Sun 13/1209:55 -

2 stops18h 45m

Deal found 28/8£653

Thu 10/908:45 -

2 stops28h 00m

Thu 8/1009:40 -

2 stops28h 15m

Deal found 28/8£669

Tue 1/1219:25 -

2 stops16h 20m

Mon 14/1209:55 -

2 stops18h 45m

Deal found 28/8£678

Fri 23/1012:35 -

2 stops26h 35m

Tue 3/1119:05 -

2 stops30h 30m

Deal found 30/8£683

Mon 28/918:55 -

1 stop16h 15m

Fri 22/121:30 -

1 stop16h 45m

Deal found 30/8£684

Find flight deals from Heathrow to Siem Reap

Round-trip from	£609
One-way from	£340
Popular in	December
Cheapest in	July
Average price	£765

Austrian Airlines
3/12-14/12
4 total stops
64h 55m total
London to Siem Reap

Search Deals

7/9
3 total stops
39h 15m total
London to Siem Reap

Search Deals

Highest demand for flights based on searches. 9% potential increase in price (£62 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 September 2026

Search Deals

Cheapflights Fare Finder

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 London Heathrow - SAI Siem Reap–Angkor Intl

LHRSAI

London Heathrow

Fri 27/11

11:00-19:40

1 stop25h 40m

Siem Reap–Angkor Intl

Tue 15/12

17:55-07:15

2 stops44h 20m

£782

Fastest return journey

LondonSiem Reap

LHR London Heathrow - SAI Siem Reap–Angkor Intl

LHRSAI

London Heathrow

Thu 3/12

11:00-20:30

1 stop26h 30m

Siem Reap–Angkor Intl

Mon 14/12

18:40-07:15

1 stop19h 35m

£782

LondonSiem Reap

LHR London Heathrow - SAI Siem Reap–Angkor Intl

LHRSAI

London Heathrow

Wed 30/9

09:05-21:30

2 stops30h 25m

Siem Reap–Angkor Intl

Mon 25/1

13:20-13:50

2 stops31h 30m

£797

LondonSiem Reap

LHR London Heathrow - SAI Siem Reap–Angkor Intl

LHRSAI

London Heathrow

Tue 10/11

11:00-20:30

1 stop26h 30m

Siem Reap–Angkor Intl

Thu 3/12

17:05-07:15

2 stops21h 10m

£801

LondonSiem Reap

LHR London Heathrow - SAI Siem Reap–Angkor Intl

LHRSAI

London Heathrow

Fri 25/9

19:30-18:55

2 stops17h 25m

Siem Reap–Angkor Intl

Tue 29/9

19:35-07:55

2 stops42h 20m

£808

LondonSiem Reap

LHR London Heathrow - SAI Siem Reap–Angkor Intl

LHRSAI

London Heathrow

Fri 25/9

09:05-21:30

2 stops30h 25m

Siem Reap–Angkor Intl

Tue 29/9

23:50-20:15

2 stops26h 25m

£816

LondonSiem Reap

LHR London Heathrow - SAI Siem Reap–Angkor Intl

LHRSAI

London Heathrow

Tue 10/11

11:00-20:30

1 stop26h 30m

Siem Reap–Angkor Intl

Sat 5/12

21:30-07:15

2 stops40h 45m

£828

Cheapest one-way

LondonSiem Reap

LHR London Heathrow - SAI Siem Reap–Angkor Intl

LHRSAI

London Heathrow

Mon 7/9

22:10-18:05

2 stops37h 55m

£361

LondonSiem Reap

LHR London Heathrow - SAI Siem Reap–Angkor Intl

LHRSAI

London Heathrow

Wed 4/11

06:00-15:00

3 stops26h 00m

£406

LondonSiem Reap

LHR London Heathrow - SAI Siem Reap–Angkor Intl

LHRSAI

London Heathrow

Sat 14/11

20:05-09:55

2 stops54h 50m

£467

Flights are sorted by cheapest return flights first.

Deals found on 31/8

Showing 1-10 of 12 resultsSorted by cheapest first

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.

LHR-SAI

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

LHR-KHSI

LHR-SAI

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 £684). Flying from London Heathrow Airport to Region of Siem Reap in July is currently the most expensive (average of £904). 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.

Reviews of airlines servicing Siem Reap

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

1,591 reviews

Check prices

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

1,591 reviews

Singapore Airlines

8.2

Very Good

1,591 reviews

Check prices

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

418 reviews

Singapore Airlines

8.2

Very Good

1,591 reviews

Check prices

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

286 reviews

Singapore Airlines

8.2

Very Good

1,591 reviews

Check prices

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

948 reviews

Singapore Airlines

8.2

Very Good

1,591 reviews

Check prices

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

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 40m. Vietnam Airlines provides one of the quickest options available for as low as £782. 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?
£376 is the cheapest one-way deal found within the past few days, from Austrian Airlines. You may also be able to find cheap deals on Vietnam Airlines and Singapore Airlines, with prices starting from £448 and £500, 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 £684). Flying from London Heathrow Airport to Region of Siem Reap in July is currently the most expensive (average of £904). 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

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Alternative routes for Heathrow to Siem Reap

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Gatwick to Krong Preah Sihanouk flights

Heathrow to Krong Preah Sihanouk flights

Top 4 airlines flying from Heathrow to Siem Reap

Airline	Cheapest	Average	Flexibility	On-time
Austrian Airlines	Cheapest£535	Average£682	FlexibilityNo cancel fee	On-time78%	Search Austrian Airlines flights
Vietnam Airlines	Cheapest£612	Average£809	FlexibilityNo cancel fee	On-time81%	Search Vietnam Airlines flights
Singapore Airlines	Cheapest£659	Average£789	FlexibilityNo cancel fee	On-time81%	Search Singapore Airlines flights
Thai Airways	Cheapest£882	Average£1,014	FlexibilityNo cancel fee	On-time77%	Search Thai Airways flights

Fly with Cheapflights

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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Cheap flights from London Heathrow Airport to Siem Reap from £340

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 7/9. Fares are subject to change and may not be available on all flights or dates of travel.

Cheap flight deals from Heathrow to Siem Reap

Cheapest flights from Heathrow to Siem ReapExplore 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 1 September 2026.

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 1 September 2026.

Best flights from Heathrow to Siem ReapDiscover carefully curated flight deals from Heathrow to Siem Reap that have cost, travel time, and stopovers in mind to ensure you get the best travel experience. Data last updated 1 September 2026.

Discover carefully curated flight deals from Heathrow to Siem Reap that have cost, travel time, and stopovers in mind to ensure you get the best travel experience. Data last updated 1 September 2026.

Last-minute flights from Heathrow to Siem ReapDiscover last-minute flight deals from Heathrow to Siem Reap. Data last updated 1 September 2026 and is based on user searches.

Discover last-minute flight deals from Heathrow to Siem Reap. Data last updated 1 September 2026 and is based on user searches.

One-way flights from Heathrow to Siem ReapSearch for one-way flight options from Heathrow to Siem Reap. Find affordable one-way fares based on user searches. Data last updated 1 September 2026.

Search for one-way flight options from Heathrow to Siem Reap. Find affordable one-way fares based on user searches. Data last updated 1 September 2026.

Find flight deals from Heathrow to Siem Reap

Round-trip from

One-way from

Popular in

Cheapest in

Average price

Cheapflights Fare Finder

Use the filters below to find and compare flights from London Heathrow Airport to Siem Reap that are best for you.

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.

Cheapflights Insights

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

Reviews of airlines servicing Siem Reap

Related info for your journey

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

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

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

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

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

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

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.

Alternative routes for Heathrow to Siem Reap

See prices for flight routes from nearby airports that may be better suited for you.

Complete your trip

Complete your trip to Siem Reap by adding a car hire and/or hotel booking to your travel itinerary.

Direct flights to

Book a non-stop flight to one of these other cities located in .

Search flights from Heathrow to Siem Reap by cabin class

Find flights from Heathrow to Siem Reap, based on your preferred cabin class, be it economy, premium economy, business, or first class.

Heathrow and Siem Reap flights

Browse other Heathrow and Siem Reap flight options. Last updated on 1 September 2026.

Popular flight searches

Check out other popular destinations found by fellow travellers in 2026

Top 4 airlines flying from Heathrow to Siem Reap

Fly with Cheapflights

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

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

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

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

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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 1 September 2026.

Best flights from Heathrow to Siem Reap
Discover carefully curated flight deals from Heathrow to Siem Reap that have cost, travel time, and stopovers in mind to ensure you get the best travel experience. Data last updated 1 September 2026.

Last-minute flights from Heathrow to Siem Reap
Discover last-minute flight deals from Heathrow to Siem Reap. Data last updated 1 September 2026 and is based on user searches.

One-way flights from Heathrow to Siem Reap
Search for one-way flight options from Heathrow to Siem Reap. Find affordable one-way fares based on user searches. Data last updated 1 September 2026.