Gustaf is a distinctive boys' name in United States, ranking #11175 in 2001 with 5 recorded births. This places Gustaf in the bottom 9% of ranked US boys' names for the year. Its actual usage is classified as Rare. The name reached its all-time peak in 2007 with 11 births ranking #7265. In 2001, approximately 1 in every 388,566 boys born was named Gustaf. FALLING Recent data shows the name is currently falling.