Scenario
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, and Leadistry's live preview turns it into a ten-minute exercise: pick the SIC codes, count the active companies, segment by region and age, 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 the register, so start by listing the codes your target market actually trades under. Check adjacent 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 with the live preview
Enter each code into a Leadistry search and read the live preview: an exact count of matching active companies from a register refreshed every 24 hours, shown before you spend a single lead. Sum the codes, and you have a bottom-up company count for your TAM in minutes.
- 3
Segment by region and company age
Add region or postcode filters to size individual territories, and incorporation-date windows to split the market by maturity: how much of it is under three years old, how much is established. The same preview recalculates instantly, so you can compare segments side by side without spending anything.
- 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. Cross-reference against Leadistry's public /sic pages, which publish real per-code counts of active companies from the July 2026 register snapshot, to confirm your numbers look right.
- 5
Turn the sizing search into the prospect list
This is the part a spreadsheet cannot do: the search that sized your market is already your go-to-market list. Tick website, email, director name and LinkedIn, start with the 10 free trial leads in your best segment, and set the search to recur as new companies enter the market.
Why this works
Top-down market sizing multiplies guesses; the register lets you count instead. Every active UK company files a SIC code, a registered address and an incorporation date, so a bottom-up TAM built from live register counts is verifiable in a way analyst estimates never are. And because the counting tool and the prospecting tool are the same search, the moment the sizing says yes, execution starts from the identical filters.
Frequently asked questions
How accurate are SIC-based market counts?
As accurate as the register itself: Leadistry tracks 5 million-plus UK companies and refreshes every 24 hours, and 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 live preview shows match counts before any lead is spent, so you can test codes, regions and age windows on the free trial with no card. Leadistry's /sic pages also publish per-code counts of active companies from the July 2026 register snapshot. You only spend leads when you want 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.
Go deeper
Run this recipe today
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