How to size a UK market by SIC code
Before you launch a product, open a territory or pitch investors, one question matters: how many companies could actually buy this? The Companies House register can answer it precisely. Leadistry makes it a ten-minute job: pick the SIC codes, read the count of active companies on our /sic pages, ask the assistant whether plenty or few match in each area, and spend nothing doing it.
The recipe, step by step
- 1
Translate the market into SIC codes
Every UK company files 5-digit SIC 2007 codes with Companies House. So start by listing the codes your target market actually trades under. Check nearby codes too. Many niches straddle two or three (software companies split across 62012 and 62020, for example). The codes are the market definition, so get them right first.
- 2
Count active companies per code
Open each code's page under /sic, which publishes the count of active UK companies filed under it from the latest monthly Companies House snapshot. Sum the codes and you have a bottom-up company count for your total market in minutes. Then tell the assistant the same kinds of business: before an agent is set up, it says whether plenty or few of them match where you sell, before you spend a single lead.
- 3
Segment by region
For each code, the /sic page names the busiest registered-office post towns, so you can compare places side by side for free. Then ask the assistant about one area at a time (a town, a city or one of the 12 UK regions): before anything is set up it says whether plenty or few companies match there, and asking spends nothing.
- 4
Sanity-check the codes
SIC data has known quirks. Catch-all codes like 82990 attract companies that could not find a better fit, and some registrations are stale. Look at real companies filed under each code, using the free Companies House advanced search, to check the code holds the businesses you mean. Not every company on the register can be emailed yet, which matters if you plan to sell by email.
- 5
Turn the sizing into the prospect list
This is the part a spreadsheet cannot do. The kinds of business and area you sized are already your agent: say yes and it is set up. Every lead comes with a website and email we checked as standard, and the director's LinkedIn is included free when we can confirm it. Start with the 25 free leads in your best segment, and the agent keeps putting new companies entering the market on your Feed every morning.
Frequently asked questions
How accurate are SIC-based market counts?
As accurate as the public record itself. Leadistry tracks 5 million-plus UK companies, reads new registrations every day and reloads the whole register from Companies House's monthly file, and the /sic counts cover active companies only. The main distortion is self-classification, since companies choose their own codes. Mitigate it by summing the two or three codes your market realistically files under and excluding catch-all codes.
Can I size a market without paying anything?
Yes. The /sic pages are public and free, and they publish per-code counts of active companies from the latest monthly register snapshot. On the free trial, with no card, the assistant also says whether plenty or few companies match any kinds of business and area before an agent is set up. You only spend leads when an agent delivers the actual company records.
What does a register-based TAM miss?
Sole traders and partnerships, which never appear on Companies House. So consumer-facing and micro-trade markets are undercounted. It also counts companies, not revenue: a market of many small firms and one of a few large ones can show the same count. Use incorporation age and accounts data to add a maturity dimension before drawing conclusions.
Run this recipe today
25 free leads from the Companies House public record. No card, no demo.
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