How Long Does It Take To Write A Proposal . A research proposal is usually around 2,500 words long although there is no upper or lower limit to this. When it comes to proposals, clients are going to flip right to the price, and probably toss it aside. Part Two How Long Does It Take to Write a Grant? The Entire Grant from research.utdallas.edu Unlike the rest of your grant application, the letter can be less formal and address the reader more directly. As explained above, the proposal is one of the last steps in the project planning stage. The topic is the title of the project and gives the reader a general idea of what the thesis is all about.