Driving under the influence (DUI / DWI) is illegal in most countries in the world including the United States. In the U.S., operating a motor vehicle while having a blood alcohol concentration (BAC) by volume of 0.08% or higher is considered a DUI / DWI. A blood alcohol concentration calculator estimates the BAC of an individual by using a mathematical formula based on the alcohol intake, gender, weight of an individual, and the time they have been drinking. Most of the blood alcohol concentration calculator programs use the U.S. National Highway and Traffic Commission (NHTSA) formula for estimating the BAC. The blood alcohol concentration calculator is available freely on the internet as an internet application offered by various websites and also as a mobile application.