Current methods for measuring the physical properties of whole bacteria have been in use for decades. ARCHIMEDES brings, for the first time, the ability to measure the physical properties of individual whole bacteria with ultra-high resolution. ARCHIMEDES measures the mass and size of each bacterium with a precision of less than 1%, far beyond the Coulter counter, and simultaneously monitors the concentration and growth rate of a culture. The response of bacteria to their environment and to antibiotics can also be assessed rapidly and with ease.