How long does it take to get marijauna out of system for urine test?

Depends. Depends on how much smoking you were doing for how long, and while weight doesn't matter per se, since thc metabolites accumulate in fat, it does depend on how much fat there is. In people who smoke marijuana regularly, it can stay positive for 3 weeks +, and I have seen some heavy regular smokers stay positive for 2 months. You can buy your own test kit at any pharmacy and see for yourself.
1 month. The time will vary by person and by test as well as the amount and frequency of exposure. However, a good rule of thumb is that one month is usually sufficient. The test we use in my office is fairly sensitive and according to the manufacturer will pick up dthc, the active component in marijuana, for as many as 23 days even with only a small exposure.