As of 13 August 2026, AI can estimate a project timeline for your proposal.

What to actually do

1. Hand it to a person

   The route this page recommends

   A person who owns the outcome does this end to end, worth it when the failure is dear.

2. Use a tool built for this

   Second choice

3. Do it yourself

   The distant third

   A chat interface, chat-fluent skill, and roughly 1 hour until you can act on the result.

   How to actually do it

   1. Open your proposal brief and write down the required outcome, every deliverable and what the client will use to accept each one.
   2. Gather the people or roles available, their realistic capacity, planned leave, working days, client availability and any fixed dates.
   3. Add previous estimates and actual durations for comparable work, then mark each figure as an estimate or an observed result.
   4. Paste the information into the prompt and ask the model to distinguish effort from elapsed time and to list missing information instead of inventing it.
   5. Compare the generated task durations, dependencies and critical path with the person who will deliver the work, correcting any assumption that does not match current capacity.
   6. Recalculate the milestone dates after those corrections and paste the checked client-facing paragraph into the proposal with its assumptions and risks included.

   Prompt

   Estimate a realistic project timeline for a UK client proposal using only the information below. Do not invent tasks, durations, people, capacity, holidays, dependencies or dates. Separate effort from elapsed calendar time, identify the critical path, and show where client decisions, approvals or external dependencies affect the schedule. If information is missing, list it as an explicit assumption or question rather than filling the gap.
   
   Project and outcome:
   [describe the project and what must be delivered]
   
   Scope and deliverables:
   [list each deliverable and the acceptance condition]
   
   Known tasks:
   [list tasks, estimated effort if known, and dependencies]
   
   Team and capacity:
   [list roles, people or available weekly capacity]
   
   Proposed start date:
   [DD/MM/YYYY or state that it is not fixed]
   
   Working calendar:
   [working days, holidays, planned leave and any client availability]
   
   Fixed dates or constraints:
   [list deadlines, approvals, procurement, third parties and other constraints]
   
   Comparable project data:
   [paste previous estimates or actual durations, if available]
   
   Produce:
   1. A concise estimate suitable for a proposal.
   2. A table with phase, task, owner or role, effort, dependency, earliest start and earliest finish.
   3. Key milestones and the critical path.
   4. A range or confidence note based only on the evidence supplied.
   5. Risks that could move the date and the action needed to reduce each risk.
   6. A short list of questions I must answer before making a firm promise.
   7. A client-facing timeline paragraph that clearly labels assumptions and does not present uncertain dates as guaranteed.

   Open it prefilled in ChatGPT or Claude, or copy it into Gemini, which takes no prefill link.