Design effort is related to three variables:

  1. Complexity of the project
  2. Design quality and sensitivity
  3. Detail required in the documentation to understand, price, contract, and build

These three corners of the triangle are closely linked so that for any project, no variable will be more than one level above or below the adjacent.

For example, it's unrealistic that a school wouldn't require engineering or its forms be composed. Likewise, it would be unusual for a house to require the detailed plumbing, mechanical, and electrical engineering needed for a hospital.

So then a simple formula approximates the design fee as a sum of the three percentages from each corner multiplied by the construction budget.

This is a rough rule of thumb for calculating design fees for a project. These might be adjusted for any number of specific design requirements:

See also Working with an Architect.