How do I compare the total hours worked in a year between an 8 to 5 job and a 6 days on 3 days off position?

12 hour shifts, 6 days straight, 3 days off, v. good money, has anyone gone from normal hours to this shift pattern who could give me a better idea of some the advantages/disadvantages?
How many hours total over the year for both? What does the equation used to figure this out look like? The 8 to 5 is Mon to Fri w. normal holidays but much less money.