320 minutes, that is 5 hours and 20 minutes, whether you take it in a classroom or online through IPIRP, because the number belongs to the DMV's program requirements, not to any sponsor (providers often schedule a 6-hour session that includes breaks). Every approved course in the state runs the same minimum length, which turns which course is shortest into a question with no answer and which course is cheapest and least painful into the real one.
Online, the 320 minutes behave like New York wrote them for commuters: progress saves, sittings are yours to schedule, and sponsors break the material into timed sections so the total instruction time meets the DMV requirement however you slice it. There is no court deadline pressing on you for the standard voluntary use, since no ticket is being dismissed; you are taking it for the point reduction, the 10% insurance discount, or both benefit clocks, and completion simply starts them.
One timing note worth your attention: the point reduction applies to violations in the 18 months before completion. Finish the course, then let the benefit do its lookback; a course finished before the points exist reduced nothing.
Every DMV-approved online course we track is compared on the New York page, and the two benefit clocks are laid out on our frequency page.