Duncan is a moderately popular boys' name in England & Wales, ranking #392 in 2002 with 60 recorded births. The name reached its all-time peak in 1996 with 139 births ranking #220. Since 1996, the popularity has decreased by 56.8%. In 2002, approximately 1 in every 4,805 boys born was named Duncan. FALLING Recent data shows the name is currently falling.