As of 13 August 2026, AI can only partly estimate the cost of your software development project.

What to actually do

1. Use a tool built for this

   The route this page recommends

2. Hand it to a person

   Second choice

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

3. Do it yourself

   The distant third

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

   How to actually do it

   1. Open the project brief, user stories, acceptance criteria and any existing technical documentation, then combine the current requirements into one feature list.
   2. Gather the proposed team roles, hourly or daily rates, working hours, VAT treatment, target date, platforms, integrations and non-functional requirements.
   3. Export comparable past project estimates or actual effort and cost data, removing confidential information that is not needed for the estimate.
   4. Paste the gathered information into the prompt and label every missing item as 'NOT PROVIDED' rather than filling gaps yourself.
   5. Ask the model to produce the work breakdown, low, expected and high scenarios, arithmetic, exclusions, dependencies and validation questions specified in the prompt.
   6. Copy the estimate into a spreadsheet and compare every multiplication, total and currency assumption against the supplied rates and source data.
   7. Ask a developer or delivery manager to check the scope, technical risks, dependencies, testing effort and scenario ranges before using the estimate for approval or a client quote.
   8. Update the estimate with the reviewer’s corrections and record which assumptions, exclusions and risks remain unresolved.

   Prompt

   Estimate the cost of this software development project for a UK business. Use only the information I provide and do not invent requirements, rates, staffing, durations or external market prices.
   
   Project description:
   [PASTE DESCRIPTION]
   
   Features and acceptance criteria:
   [PASTE FEATURE LIST]
   
   Platforms, integrations and technical constraints:
   [PASTE DETAILS]
   
   Non-functional requirements, including security, performance, availability and compliance:
   [PASTE DETAILS OR WRITE 'NOT PROVIDED']
   
   Team roles and hourly or daily rates in pounds sterling:
   [PASTE RATES, INCLUDING WHETHER VAT IS INCLUDED]
   
   Known dates, working hours and delivery constraints:
   [PASTE DETAILS OR WRITE 'NOT PROVIDED']
   
   Past project data or comparable estimates:
   [PASTE DATA OR WRITE 'NOT PROVIDED']
   
   Produce:
   1. A work breakdown by phase and feature.
   2. Estimated effort for each item, showing the unit used and the reason for the estimate.
   3. Labour cost for each item and a total in pounds sterling.
   4. Separate costs for discovery, design, development, testing, project management, deployment and post-launch support where the information permits.
   5. A low, expected and high scenario, with the assumptions that create each scenario. Do not create a contingency percentage unless I provide one.
   6. A list of missing information that could materially change the estimate.
   7. Dependencies, risks, exclusions and items that need technical discovery.
   8. A short list of questions for the client or project team.
   
   Show the arithmetic clearly. Distinguish supplied facts from assumptions. Do not present the result as a quote, fixed price or delivery promise. End with a section titled 'What a technical estimator must validate' listing the parts that require review by an experienced developer or delivery manager.

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