Duncan is a moderately popular boys' name in United States, ranking #488 in 2002 with 472 recorded births. This places Duncan in the top 4% of ranked US boys' names for the year. Its actual usage is classified as Moderately Popular. The name reached its all-time peak in 1997 with 644 births ranking #378. In 2002, approximately 1 in every 4,113 boys born was named Duncan. FALLING Recent data shows the name is currently falling.