I've been working hard at trying to get my house more energy efficient etc.

How can I find out how much my Carbon Offset is?

http://www.carboncounter.org/offset-your-emissions/personal-calculator.aspx

I really like the calaculator but find the personal air travel one impossible.
a fully loaded p737 with fuel and freight weighs about 48 metric tonnes.
there are about 189 passengers.

The maximum number of tonnes of output can not be greater than the input via simple math, chemistry and physics. yes they are pilling O2 from the atmosphere but they are also giving off water and other gasses.

They need to recalculate. Based on Modern jet engines and planes.