SPG Starpoints now transfer to 33 airlines with the addition of Korean SkyPass Miles to the list. Korean SkyPass is a 1:1 transfer partner, and, as with all 1:1 transfer partners, for every 20,000 points transferred, you get 5,000 bonus miles.

Examples:

15,000 Starpoints = 15,000 Korean miles
20,000Starpoints = 25,000 Korean miles
25,000 Starpoints = 30,000 Korean miles
60,000 Starpoints = 75,000 Korean miles

You can transfer Starpoints to airline miles here.