Originally Posted by
drnp
For the record, I believe you get 15000 miles for 20000 starpoints if the relationship is 2:1
No.
When you transfer 20000 starpoints to the airline program, SPG will deduct 25000 starpoints from your account first, then add 5000 starpoints as bonus to your account. They are not adding 5000 airline miles.
Thus by this logic you will get 12500 CO miles.