How long does alcohol stay in your system after drinking 8 shots?

One beer contains approximately 2 units of alchohol (volume x percentage alcohol / 1000) (500ml for a proper pint x 4% / 1000). The body is able to metabolize approximately 1 unit of alcohol per hour (very different from individual to individual since it depends on genetics, age, weight, etc). So, 8 beers x 2 units = 16 units = 16 hours