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Cheap flights from London Heathrow Airport to Siem Reap

LHR — SAI
29 Oct — 5 Nov1
1 adult
1 adult, Economy, 0 bags

Find flight deals from Heathrow to Siem Reap

Popular in

December

Cheapest in

July

Average price

£779
Highest demand for flights based on searches. 6% potential increase in price (£46 potential increase over avg. return price).
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Cheapest flight prices on average. 3% potential price decrease (£23 potential savings vs. average return price).
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Average for round-trip flights in September 2026
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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, September is the cheapest month in which you can book a flight from London Heathrow Airport to Region of Siem Reap (average of £703). Flying from London Heathrow Airport to Region of Siem Reap in July is currently the most expensive (average of £923). 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
1,618 reviews
Check prices

Entertainment

8.1

Crew

8.7

Comfort

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
1,618 reviews
Singapore Airlines
8.2
Very Good
1,618 reviews
Check prices

Entertainment

8.1

Crew

8.7

Comfort

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
425 reviews
Singapore Airlines
8.2
Very Good
1,618 reviews
Check prices

Entertainment

8.1

Crew

8.7

Comfort

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
291 reviews
Singapore Airlines
8.2
Very Good
1,618 reviews
Check prices

Entertainment

8.1

Crew

8.7

Comfort

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
7.5
Good
974 reviews
Singapore Airlines
8.2
Very Good
1,618 reviews
Check prices

Entertainment

8.1

Crew

8.7

Comfort

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

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

    £384 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 £458 and £511, 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, September is the cheapest month in which you can book a flight from London Heathrow Airport to Region of Siem Reap (average of £703). Flying from London Heathrow Airport to Region of Siem Reap in July is currently the most expensive (average of £923). 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

Top 4 airlines flying from Heathrow to Siem Reap

AirlineCheapestAverageFlexibilityOn-time
Austrian AirlinesCheapest£547Average£697FlexibilityNo cancel feeOn-time78%
Search Austrian Airlines flights
Vietnam AirlinesCheapest£625Average£826FlexibilityNo cancel feeOn-time81%
Search Vietnam Airlines flights
Singapore AirlinesCheapest£673Average£814FlexibilityNo cancel feeOn-time81%
Search Singapore Airlines flights
Thai AirwaysCheapest£902Average£1,013FlexibilityNo cancel feeOn-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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