<p>16 units is the bare minimum if you want to be able to graduate in the normal (8 semester, no summer semesters) timespan, as 16 x 8 = 128, and most degrees require at least 128 units. 12 units is the minimum you need to be enrolled in to be considered a full-time student, and I believe different departments have different requirements for how many units per semester is considered “satisfactory progress.” </p>
<p>Depending on your major, your major may have lots of 2 credit electives (e.g. Music Industry, Interactive), so that’ll affect your choices… Honestly, 18 units really isn’t that much work, though.</p>