It works like this:
Points = {0.5 or 1.0 or 1.5} * Miles

The multiplier is 0.5 for cheap coach tickets, 1.5 for premium cabin and full-fares, and 1.0 for other coach fares.

In your case,
0.5*500 + 0.5*508 + 1.5*814 = 1725

Note that you can qualify on points OR miles. So if you want to qualify on miles, you can totally ignore the points system.