According to Google and Airliners.net, the A330-300 burns approximately 6,000 kg of Jet-A per hour at cruise, so let's use that as an average burn rate since fuel consumption is higher during different phases of flight (e.g., takeoff) and lower during others. That's 7,500 liters per hour at 1.25 L/kg for Jet-A.

The fuel consumption of an Airbus A330 varies based on the specific model (the older A330-200/300 vs. the newer A330neo), the weight of the aircraft, and the atmospheric conditions, but a general average for a standard A330-300 is approximately 5,600 to 6,000 kilograms (about 1,800 to 1,950 gallons) of jet fuel per hour of flight. To put that in perspective, that is roughly 100 kilograms of fuel every minute. The newer A330neo (A330-900) is significantly more efficient, burning about 14% less fuel per seat than its predecessors thanks to its advanced Rolls-Royce Trent 7000 engines and aerodynamic "sharklet" wingtips. This brings the hourly burn down to roughly 4,800 to 5,200 kilograms. Factors like flying against a strong jet stream or carrying a full load of passengers and cargo will push these numbers to the higher end of the range. Airlines track these numbers to the gram, as fuel typically accounts for 20% to 30% of an airline's total operating expenses. For a typical 8-hour transatlantic flight, an A330 might consume over 45,000 kilograms (100,000 lbs) of fuel, which highlights why the industry is so focused on sustainable aviation fuels and more efficient engine designs.