Calculating Avios
I'm confused about how Avios are calculated and I am looking for some simple rules of thumb as to how many avios point I should see on my account. My confusion arises as sometimes I have one avios amount awarded for a return flight (2 sectors) and sometimes I have 2 avios amounts which I assume is the outward and inward legs of the trip. Also, avios for identical trips (fare basis and route) show up with different avios amounts. Therefore I am a bit at sea as to what I should expect to see. So, taking the below made up example, can someone calculate what my avios balance should be. Also if someone can confirm if I should see avios for each leg of a return flight or only one balance covering the outward and inward legs.
Example. DUB-LHR
Price of outward leg EUR 50
Price of the inward leg EUR 100
Total fare is EUR 150 broken down by fare of EUR 100 and Taxes and Charges of EUR 50.
Any help greatly appreciated.