Duncan is a moderately popular boys' name in England & Wales, ranking #490 in 2003 with 49 recorded births. The name reached its all-time peak in 1996 with 139 births ranking #220. Since 1996, the popularity has decreased by 64.7%. In 2003, approximately 1 in every 6,113 boys born was named Duncan. FALLING Recent data shows the name is currently falling.