How many miles do i need to achieve before getting a free miles?

Question

How many miles do i need to achieve before getting a free miles?

Answer 1

each airlines have there rules , each one are different ......

2500 miles unless airlines changed there rules ....

Answer 2

When collecting miles it is best to stick with one airline so your quickly progress up the ranks.  Once you move from Silver to Gold it becomes easier to get miles.  

For an upgrade for an 8-10 hour flight it normally would cost about 20,000 to 25,000 miles.  A free flight in coach would be about 60,000 return.