To determine the total cost of something by calculating all the smaller costs involved. A noun or pronoun can be used between "cost" and "up." When we cost up all the steps of our home renovation project, we knew that it was going to exceed the amount we had budgeted. The boss wants you to cost up the project before he'll sign off on it.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.