In its most basic form, productivity is the measure of output versus input. In manufacturing, this relationship often takes the form of units produced compared to the number of man-hours required. The resulting ratio offers a measure of productivity, but it's only useful when you have a comparison or an expected value. If you know the maximum output possible, then this ratio can be further used to calculate the percent efficiency.

Calculating Production Pieces

The number of pieces produced is simply a total in the period of time you wish to evaluate, such as an annual, monthly, weekly or daily period. If you wish to establish an average number of units produced per man-hour for comparison purposes, count all units produced by all employees. If you need to evaluate a single employee, only count the pieces produced by that employee.

Calculating Man-Hours

You should total the paid man-hours that contributed to the previously counted production total. If you were calculating an average, count all man-hours for that particular period. As an example, if five employees worked 40 hours each to produce the week's inventory, multiply 5 times 40 to calculate 200 man-hours. To evaluate a single employee, only count his hours.

Calculate Productivity

By dividing the number of products produced by the man-hours involved, you calculate the average production rate. As an example, if your employees produced 800 units in the 200 total man-hours during the week, divide 800 by 200 to calculate 4 units per man-hour. Invert this calculation to determine the average production time per unit. In the example, divide 200 by 800 to calculate 0.25 hours per unit, or 15 minutes per unit.

Calculate Efficiency

Efficiency relates to the productivity rate compared to the maximum rate achievable. The maximum rate can be difficult to assess, but one option is to use the highest production rate of any individual employee. Another option is to use a machine's maximum output assuming no human delays or errors. As an example, maybe a machine can complete 10 units per hour if the process isn't delayed by loading individual materials, inspecting units, or maintaining the machine. Divide the previously calculated production rate by the maximum rate and multiply by 100 to calculate the efficiency rate. In the previous examples, divide 4 by 10 and multiply by 100 to calculate an efficiency rate of 40 percent.