custom formula for duration

[ericfons]

Consider the following scenario:



I am a flooring contractor and I track all my jobs as
one MS project. I am planning work for 2 homes where home 1 (H1) is 1000 sq feet, and home 2 (H2) is 2000 sq feet.

It takes one person-day to finish 500 sq feet. When I create a new task for H1, I simply want to enter 1000 sq ft in a field as an input about H1 and then I want MS project to calculate 1000/500 = 2 days as the duration for H1.

Similarly, I want to enter 2000 sq ft in a field an input about H2 and then I want MS project to calculate 2000/500=4 days as the duration for H2.

I know how to create a custom field. This would the area (square feet) of a home, say, homeArea. What I do not know is how make MS Project set the duration field automatically = homeArea/500

Please help.