Dulles International (IAD) to Heathrow (LHR).
| Departure | Return | Price |
|---|---|---|
| 08/04/2026 | 08/13/2026 | $791 |
| 07/18/2026 | 07/23/2026 | $847 |
| 07/22/2026 | 07/29/2026 | $847 |
| 07/24/2026 | 07/30/2026 | $847 |
| 07/28/2026 | 08/04/2026 | $847 |
| 07/30/2026 | 08/04/2026 | $847 |
| 07/31/2026 | 08/06/2026 | $847 |
| 08/01/2026 | 08/06/2026 | $859 |
| 08/05/2026 | 08/13/2026 | $862 |
| 08/05/2026 | 08/12/2026 | $868 |
Based on current fares, August is the cheapest month to fly from Washington DC to London, with average fares around $856 round trip (as low as $791).
June tends to be more expensive, averaging $1041.
See the full month-by-month and day-of-week price analysis
Best Time to Fly IAD → LHRDeparture date prices (economy, round trip). Green = cheap, red = expensive.
The cheapest month to fly from Washington DC to London is August, with average round-trip fares around $856. Fares in August start as low as $791. The most expensive month is June, averaging $1041.
A nonstop flight from Washington DC to London takes approximately 7h 30m.
The cheapest flight from Washington DC to London currently starts at $791 round trip in economy class.
The average round-trip flight price from Washington DC to London is $1047 in economy class.
The distance is 3666 miles (5899 km). with a nonstop flight time of about 7h 30m. The lowest fare currently available is $791 departing in August. The average round-trip fare is $1047.
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