EQD on AA is simple. It's what you paid for the ticket minus taxes,
including airline surcharges and such.
This is if you buy your ticket through AA, even if it's a codeshare or not on their metal. This is because they know what they charged you for the ticket.
Now if it's on another carrier from their partner list, this is where it can get confusing. You have to look up the airline on their partner page (
located here) and go by the chart. The chart will show how to calculate what you will earn which is based on the actual miles flown.
You check the table against your booking code and then do a little math.
Say you have a 6k mile segment on BA, and you paid $3200 for a business ticket with a booking code of J.
EQM: 6000 miles x 1.5 EQM/mile = 9000 EQM.
EQD: 6000 miles x .25 (25% EQD/mile) = $1500.
So for that one segment you would get a credit of 9k EQM and $1500 EQD. If it was r/t, then that would be 18k EQM and $3k EQD.
So if you paid $3200 for your ticket, you come out about the same as you would on AA as there wast probably $200 worth of taxes or a little more. Now if that same ticket was $1k cheaper, you would end up coming out ahead of the game by being on a partner flight, as the EQD on AA would only be $2k minus taxes.