Will your urine test be clean after 11 days of not smoking marijuana?

This depends on the frequency of use. A frequent or habitual users will take much longer to clean out their system than a person who occasionally uses it. Since THC is stored in fat cells a persons metabolism and size should also be taken into account. So for someone who smokes on occasion and, for sake of argument, is in decent shape, it would take about 7-10 days. It would be very unlikely for an average person to be clean in 11 days, though it has happened in some cases. The best bet is to not chance it, and not use it to begin with.