As of 13 August 2026, AI can only partly estimate the size of your UK market.
This still needs a person who signs their name to it.
Can you do it?
15 minutesto a draft.
1 hourto something you’d act on.
Cost, all in£0
Skill neededchat-fluent
Who has to check ityou
What the alternative costsA market-research specialist can validate the assumptions and sources; the supplied tool information gives no price for that service.
If this goes wrong: you overestimate demand and commit budget to a market that cannot support your sales target.
What to actually do
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.
Use a tool built for this
Second choiceDo it yourself
The distant thirdA chat interface, chat-fluent skill, and roughly 1 hour until you can act on the result.
How to actually do it
- Define the market in a short brief covering the UK geography, customer type, product category, time period, price and what counts as a potential customer.
- Open your internal sales, customer, survey and website analytics records, then collect the figures that describe current customers, usage, conversion and average spend.
- Find current UK source material relevant to the definition, such as official statistics, trade bodies, company filings or published industry research, and save the links and the exact figures or extracts.
- Paste the brief, internal data and source extracts into a chatbot with the supplied prompt, asking it to calculate a bottom-up estimate and label unsupported inputs.
- Copy the resulting assumptions, arithmetic and source list into a spreadsheet and recalculate each step using the cited figures rather than the model's displayed totals.
- Compare the market definition and scenarios with your actual offer, sales capacity and customer evidence, then replace unsupported assumptions or mark the estimate as unverified.
- Send the final estimate and its evidence table to a colleague who understands your market before using it for targeting, forecasting or budget decisions.
Prompt
Estimate the size of the UK market for [product or service]. Use this scope: - Customer type: [businesses or consumers, and any relevant characteristics] - Geography: [UK-wide or named UK regions] - Time period: [year or period] - Market definition: [what counts as part of the market] - Offer and price: [description and current price, if relevant] - Intended customer count or usage assumption: [details, if known] - Internal data: [paste sales, customer, survey or website data, or write "none"] - Sources I provide: [paste links, extracts or reports] Build a transparent bottom-up estimate where possible. If a top-down estimate is also useful, show it separately and explain why the two approaches differ. State every assumption, distinguish sourced facts from estimates, show the arithmetic, use pounds and UK-specific sources, and do not invent figures or sources. Flag missing inputs and give low, central and high scenarios only when the available evidence supports them. Separate total addressable market from the realistically reachable market. End with a short list of the three assumptions that most affect the result and the exact evidence I should collect to test them.
Open it prefilled in ChatGPT or Claude, or copy it into Gemini, which takes no prefill link.
What it gets wrong
- It cannot guarantee that public market figures use the same customer and product definitions as your business.
- It cannot access private customer behaviour, unpublished competitor data or paid research unless you provide the material.
- It cannot decide whether an assumption about adoption, frequency or willingness to pay is commercially realistic.
- It can present precise arithmetic around a weak assumption, making an uncertain market look more authoritative than it is.
What caps this at PARTLY: real time truth, verification cost and judgement under ambiguity.
How we scored this
Five axes, each scored nought to two by hand: ten means AI carries the task cleanly, and the thresholds that turn a total into YES, PARTLY or NO are published in the methodology. Each axis name links to its definition.
| Axis | Score (0–2) |
|---|---|
| Output | 2 |
| Inputs | 1 |
| Verification | 1 |
| Liability | 1 |
| Effort delta | 1 |
| Total | 6 / 10 |
The methodology and its thresholds are published in full.
FAQ
- Can ChatGPT calculate my total addressable market?
- Yes, it can structure a total addressable market calculation from figures and sources you provide. It cannot make the definition or evidence reliable for you, so check that each source measures the same customers, geography and product category.
- How do I estimate the size of a UK market?
- Define the customer and product narrowly, gather current UK evidence, then calculate the market from the number of potential customers, expected usage and price. Use AI to show the arithmetic and scenarios, but validate the sources and assumptions before making a commercial decision.
- Can AI estimate my serviceable obtainable market?
- It can model a serviceable obtainable market if you provide realistic limits such as geography, sales capacity, channels and likely conversion. It cannot know whether those limits reflect your actual competitive position without evidence from your business and market.
- Can AI use market research to forecast UK demand?
- It can summarise supplied research and turn its assumptions into a demand scenario. A forecast is not a fact, and you must check the research date, sample, definitions and relevance to your offer before relying on it.
Nearby answers
Assessed by gpt-5.6-luna (gpt-5.6-luna) on 2026-08-13, second-checked by an independent model. Wrong somewhere? Email [email protected] and it gets re-checked.
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