Cardiff, AL has a population of 58 and is the 27,989th largest city in the United States. The population density is 231 per sq mi which is 152% higher than the Alabama average and 155% higher than the national average. The median age in Cardiff is 18 which is approximately 55% lower than the Alabama average of 39. In Cardiff, 97% of the population over 15 years of age are married, 100% speak English and 0% speak Spanish. 95% of Cardiff residents were born in Alabama, 5% were born out of state, 0% were born outside of the United States and 0% were foreign born.