Calculate the average time spent on a computer by a student. As an example, you could monitor computer usage for 50 students at various times. If the sample time totals 1,000 minutes, dividing by 50 gives you an average usage time of 20 minutes per student.
Divide your computer lab's hours into logical periods. These periods might mirror class periods or blocks of one or more hours. As an example, if your computer lab was open from 7 a.m. to 7 p.m., you might divide the day into 12 discrete hours.
Multiply the amount of time in each period by the number of computers. This gives you the total computer time available per period. Divide this total by the average computer usage per student to calculate the total blocks of time available per period. For example, if the computer lab contained 10 computers, multiply 10 by the 60-minute time period to get 600 computer minutes per period. Divide 600 by the 20-minute average computer usage to get 30 blocks per period.
Count the number of students using the computer lab during each period. If a class reserves the computer lab for a period, count that period at full capacity, or the total blocks of time available. In the example, a reserved period counts as 30 blocks.
Divide the number of students per period by the total time blocks available. Multiply the result by 100 to calculate the period's usage percentage. In the example, 15 students divided by 30 blocks gives you a usage of 50 percent. A scheduled class counts as 100 percent.
Average each equivalent period's usage percentages to calculate that period's total percent usage. This average should span an entire quarter, semester or year, depending on your school's course schedule.
Average the usage percentage of all periods to calculate the computer lab's overall usage percentage.