“How long is staph contagious?”

It is impossible to ever determine how long a patient remains contagious after contracting an infectious disease. For staph infections, depending on the location, some individuals remain "colonized" and so can transmit the bacteria to others long term. Some infectious agents are transmissible before symptoms appear, which increases the likelihood of transmission to other vulnerable individuals. It is likely that one remains contagious so long as symptoms are present, but how long before or after, that is impossible to generalize.

Shelley C. Springer, MD, MBA, MSc, JD, FAAP

Usually contagious until lesions are scabbed over and dry, assuming it's impetigo from staph.

Generally, he is considered to be contagious till on antibiotics/treated for 24 hours plus no purulent discharge present.