Two weeks is professional general standard, but a lot of companies consider the two week period a starting point, and you may want to consider giving more notice if you think your current job or coworkers would be seriously impacted by your quick departure. This all depends on how senior you are, what you do, and ultimately how you want to leave your relationships as you depart. If your role is critical or specialized you may want to give your current employer a heads up on your departure and open a discussion on what sort of notice would work best for both parties. If you lead a team, your departure may be more of an obstacle for them vs. you, so you may need to weigh your notice amount against how much time your team will need to make a smooth transition, and go from there.