Over the past 110 years, 48 863 boys and 1 500 girls have been named Colby. The name Colby ranks 445th in the United States among the most common names for boys. For the first time more than ten times newborns were named Colby in 1917. The peak of popularity of the name Colby came in the 1990s and 2000s. You can see absolute numbers and relative numbers on the chart. Indicators per 100K more accurately assess the popularity of the name.