Flight time: London to Sydney

Route details

Distance breakdown: London to Sydney

The 17,020-km great-circle distance between London (51.47°N, 0.45°W) and Sydney (-33.95°N, 151.18°E) spans 85.4° of latitude and 151.6° of longitude, trending primarily east. In miles, this is 10,576 mi or 9191 nautical miles. The great-circle path — the shortest distance over Earth's curved surface — is calculated using the Haversine formula from the two airports' precise coordinates.

Cruise speed and flight phases

On this 17,020-km long-haul route, aircraft spend the majority of the 19h 25m to 21h 35m journey at optimal cruise altitude of 35,000–42,000 feet, where modern wide-body jets achieve true airspeeds of 820–900 km/h (Mach 0.82–0.86). The initial climb and final descent represent a smaller fraction of total flight time compared to shorter routes. Aircraft like the Boeing 777, 787, or Airbus A350 typically operate routes of this distance, with step climbs during the flight to reach progressively more efficient altitudes as fuel burns off and the aircraft lightens.

Ground time and routing overhead

Our 30–50 minutes overhead allowance covers: taxi-out at LHR, takeoff and initial climb, descent and approach at SYD, and taxi-in to the gate. LHR is a major international hub where taxi times of 15–25 minutes are common during peak periods. At SYD, arrival taxi and gate assignment can add 10–20 minutes, especially during busy arrival banks. Continental air traffic corridors between London and Sydney may add 3–8% beyond the great-circle distance. Standard instrument departures and arrivals at both airports use predefined routing that adds distance but ensures safe separation.

Return flight: Sydney → London

The return flight from Sydney to London is generally similar in duration to the outbound — typically within 10–20 minutes. Continental routes like this one are less affected by the jet stream asymmetry that makes oceanic east-west routes so uneven. The main variables affecting any difference are: prevailing winds at these latitudes (modest effect), different standard instrument departures/arrivals at each airport (minor effect), and air traffic congestion patterns that vary by time of day and direction.

Seasonal variation in flight times

Flight times between London and Sydney vary modestly by season — typically 10–20 minutes. Upper-level wind patterns shift with the seasons: winter generally brings stronger westerly winds at these latitudes, while summer patterns are more variable. Thunderstorm activity along the route corridor peaks in summer months, occasionally causing routing diversions that add distance. Winter operations may include de-icing delays at LHR, which extend the overall gate-to-gate time.

Airport information

Heathrow Airport (LHR) is a major international hub in London, United Kingdom. As a tier-1 airport, it handles high traffic volumes, which means longer average taxi times but also higher flight frequency and competition that can benefit travelers on pricing. Sydney Kingsford Smith Airport (SYD) is a major international hub in Sydney, Australia. As a tier-1 airport, it handles high traffic volumes, which means longer average taxi times but also higher flight frequency and competition that can benefit travelers on pricing.

Flight times from London to other destinations

Flight time FAQ: London to Sydney