Courtesy of Air Canada and the US EPA.

Figures are based on diesel instead of aviation fuels. But if someone has the numbers, feel free to add them.

1. Go to the Air Canada "zerofootprint" calculator

2. Enter your itinerary and click on "Calculate My Emissions"

3. Take the "Total Emissions" number (in tonnes) and multiply it by 457 (based on 22.2 lbs/US Gallon for diesel, according to the US EPA)

The resultant number is the number of litres you personally will "consume" on that itinerary.

So, for example, YYC-YVR one-way would burn about 46 litres of fuel, while YVR-SYD would burn 594 litres. If you multiply that by a full load of 270 passengers you get a fuel requirement of 160,353 litres, not including the crew. (It's less than 270 x 594 because the actual burn is slightly less than 594 litres per person.)

Add in 20 crew members (my guess, and it's only a guess -- feel free to correct) and total burn is 172,231 litres. According to the AC fleet page, the 77L used on that route has a fuel capacity of 202,287 litres.