How long will 3 mg of clonazepam stay in your system?

Few days: Clonazepam has a relatively long half-life (18-50 hours) so a few days most likely but a host of factors - how long it was taken and how much is stored in the body, your body's efficiency in breaking down and clearing the medication, etc. Talk with your prescribing doc about your concerns to get a better idea and share why you'd be worried about this issue so he/she can be most helpful to you.