You may find yourself at a point in your life where, for whatever reason, you need to volunteer some service hours to your community. Certain high school classes may require a certain number of volunteer hours. Likewise, you may need to complete volunteer hours on a court order. You can calculate the number of hours you volunteered in a very specific way.
Find out how rounding is handled in your specific situation. Certain volunteer programs will allow for a degree of rounding -- for example, 1 hour and 45 minutes can be rounded up to 2 hours. However, certain situations (like those that are court ordered) will allow for no rounding at all.
Go through your volunteer sheets and convert all of your volunteer sessions from hours to minutes. Many volunteer programs require you to get the signature of a supervisor after each session to validate your hours. These signature sheets will have the total number of hours for particular days contained on them. For example, if one day you volunteered for 1 hour and 30 minutes, converted to minutes that would be 90 (because there are 60 minutes in one hour).
Add up all the minutes you calculated in "Step 2." For example, if you volunteered for four days at 90 minutes, 75 minutes, 50 minutes and 25 minutes each day, 90 + 75 + 50 + 25 equals 240 minutes.
Divide the number of minutes you added by 60 to convert it to hours. For example, 240 minutes divided by 60 equals 4 total hours of volunteer work.