I have used Microsoft Project for years and am still an average user. A frequent question I ask myself when I am doing a new project plan from scratch is, Am I working with work or duration?

It is easier to do planning with duration. Then as you assign resources, you level set with the work estimates for individuals, adjust for overhead time, vacations, holiday schedules and other factors. This includes external such as vacation time and Fridays with people slowing down on warm sunny summer days. But also internal factors such as people who always under or over estimate. As a project manager, one of your jobs as the PM is to convert under estimates under reality time, and trim the fat out of over estimates. This is the P for people part of Project Management.

Work is the length of time it actual takes you to do a task. If it takes 16 hours to do an engine repair, then the work is 16 hours.

Duration is the actual time that passes for the task to be complete. If the work for the engine is 16 hours, and 1 mechanic works on it, the duration could be 2 days if the do nothing else. 3 days if they have to put tools away and bring them back out at the start and end of each day, clean up the shop area, and go to the bin for parts and the crib for tools.

If two mechanics work for 8 hours each then the duration could be 1 day, but the work is still 16 hours.

Work estimates are a science and a passion all to themselves. Ask anyone who worked for a major manufacturing company such as Ford or Trailmobie, or worked at any of the thousands of local auto dealership repair departments.

Which is better to get, work or duration? When I am in project estimate phase involved in business justification or long term planning, I want durations. Once the project is green lighted, I want work estimates. It takes longer to get a work estimate then a duration, and work is more accurate. A savvy project manager knows to let people who which they want, and lets the resource or resource manager know how much effort to put into the requested estimates.

Don’t bother people asking for 15 minute increment work estimates on a year long project that hasn’t been approved yet. And don’t ask twice for duration and then work on a 2 week project. Expect them to be pretty close.

When you put the estimated hours into Microsoft Project, enter the work effort. Project calculates duration for your automatically. Next look on the project’s critical path for areas that are in need of adjustments.

The more you use Microsoft project the better you can get with the tool. But it is still just a tool. Learn to ask for what you need, and remember how well people did last time around, so you can convert Jim time into reality time.