Sulphur, OK has a population of 5,042 and is the 6,435th largest city in the United States. The population density is 735 per sq mi which is 1247% higher than the Oklahoma average and 712% higher than the national average. The median age in Sulphur is 36 which is approximately equal to the Oklahoma average of 36. In Sulphur, 53% of the population over 15 years of age are married, 94% speak English and 5% speak Spanish. 69% of Sulphur residents were born in Oklahoma, 27% were born out of state, 0% were born outside of the United States and 3% were foreign born.