Estimating Productive Hours per DayWritten by Tom Mochal
Estimating Productive Hours per Day
Estimating is one of the most critical aspects of project management. A project management methodology will help you develop estimates using a common process and techniques. There are three major elements of project estimating - effort, duration and cost. You must start with an estimate of effort hours. Duration can then be calculated by looking at the effort and the number of resources that you can apply. For example, one person may be able to complete an 80-hour activity in two weeks. Two full-time resources could complete the work in one week.
"Productive" Hours Per Day
Another factor in converting effort hours to duration is to define how many productive hours of work you can expect in a typical workday. For example, if you have an activity that you estimate will take forty effort hours; it is unlikely that it can be completed in five eight-hour calendar days. No one is 100% productive. You need a "reality factor" to convert the estimated effort hours to estimated duration.
Employee Productive Hours
A productivity factor takes into account the amount of time a typical person will actually work in a day. This productivity factor assumes things like social interaction with colleagues, going to the bathroom and traveling to meetings. It also factors in the time people need to ramp up in the morning, as well as people that start to fade in the late afternoon. A generally accepted rule-of-thumb for average productive hours per day is 6.5, based on an eight-hour day. This is an 80% productivity factor.
Contractor Productive Hours
When you have contract resources, you should also take a productivity factor into account. Even though these resources are contractors, they will still experience many of the factors that lead to a less than 100% productivity factor. For instance, they are still going to socialize a little and they still need to go to the bathroom. A good rule of thumb for a contract resource is 7 to 7.25 productive hours per day. This factor recognizes that the contract resources are not robots and they will not be 100% productive every day. Of course, you still need to pay them for eight hours per day. However, for the purpose of your schedule, you should factor in the productivity factor as well.
Let’s look at an example. Let’s say you have an activity that is estimated to take 80 hours of effort. If an employee is applied full time, it may take him or her a little over twelve days (80 / 6.5 productive hours per day) to complete the work. If a contract resource is allocated full time to this same activity, the activity duration would be eleven days (80 / 7.25 productive hours per day).