What i usually do is park the car 25ft away from a white wall and mark the low beam pattern. Usually this also allows you to actually adjust the lights properly if you know the technique.
Once I've marked the stock halogen line for each side, I swap the led and see if the cutoff line is the same. Usually due to the brighter light output, I turn the rotating screw a quarter and lower it down. This allows any unwanted glare to be neutralised. Good leds won't have this issue since they have a sharp factory cutoff but I still do it
