need help to count hours from a calendar schedule

[sumhungl0]

i need to get a total of hours from cells in a continuouscalendar type of sheet. sheet setup:dates across the top(row 1) and equipment on the left(col A, frozen). basically the body of cells have informationon what is going on for each equipment on the left under the date in the toprow. sample info cell content: oil change, scheduled usage 0900-1200. which means on that day when the equipment isnot being used it will get an oil change but it will be used from 9am tonoon. what I would like to do is have arow below all the equipment for total hours used during that day. so each cell for that day which contains thetime range"0900-1200", get the difference"1200 minus 0900 =3hrs" and then total all those values to get me a usage for that day. I would like to get this done with a cell formula but I would also like to be able to do this in vba because I do have a need to read each cell and get the hours for that equipment. not just a total for the day. so I guess my question/s are. 1. what would be the cell formula to read the hours and get the difference for all equipment for the day? if possible. might need to have a function to get these hours, not sure. 2. what vba would I use to read the hours in each cell? because I do have a need to look at hours for each equipment for the week/month/quarter/year. any ideas on this? or maybe point me in the right direction? thanks in advance.