Show the segment and the multiplication
Consider a warehouse inspection app priced per site. Its draft slide says “A large logistics market” and shows an industry spending total. That total could include transport, equipment and other spending the app will never earn. It gives context, but it does not size this subscription opportunity.
Replace it with a defined segment and a calculation: eligible independent warehouse sites in one launch region, multiplied by an assumed monthly subscription per site, annualised over twelve months. The worked slide below uses two site-count scenarios rather than presenting one precise total.
All inputs are invented for this teaching example. The region is hypothetical; neither the eligible-site counts nor the price is a researched market estimate. The range shows two assumptions, not a statistical confidence interval.
£960k–£1.44m annual subscription potential
- Eligible sites
- 800–1,200Two assumed count scenarios
- Price per site
- £100Per month · assumed price
- Annual basis
- 12Months
↳ This sizes the defined segment. It is not current revenue or a sales forecast.
Make the counting unit match the pricing unit
The example counts sites because the proposed charge is per site. If the commercial offer instead charges one fee per operator, use operators. Counting ten locations and applying an operator-level fee to each would inflate the calculation.
Write the inclusion rule beside the number: geography, customer type and the operational requirements that make a site eligible. Exclude sites outside that scope. Where customers overlap across datasets, remove duplicates before adding the counts.
Pear VC’s market-sizing guide describes a bottom-up method that connects customer numbers with annual revenue per customer. Here, the same logic is expressed per site. The multiplication is simple; choosing a defensible unit and population is the substantive work.
Put the evidence beside the inputs
In a real deck, attach the source and date to the eligible-site count, and explain how you filtered it. Label the price according to its basis: contracted price, tested proposal or planning assumption. A published list price alone does not establish what every buyer will pay.
The U.S. Small Business Administration treats demand, market size, location and pricing as separate research questions. Use that distinction: a directory can help count locations, while customer research is still needed to understand need and willingness to pay.
Keep material uncertainty visible. In the example, changing the site count from 800 to 1,200 changes the annual total by £480,000 at the same assumed price. The displayed range varies only the count; it does not cover price discounts, different packages or every source of uncertainty.
Keep market potential separate from your sales plan
The £960,000–£1.44 million result assumes every eligible site buys for a full year at £100 per month. It is annual subscription potential for this defined segment, not current recurring revenue or a forecast of what the company will sell.
Show the sales plan separately, using expected customer acquisition, start dates, retention and delivery capacity. Do not turn the market total into a forecast by applying an unexplained percentage.
If the deck also uses TAM, SAM or SOM labels, define their scope and keep the same units. A larger expansion market can sit alongside this initial segment, with the additional customers and assumptions stated. The narrower calculation should help explain the starting point, rather than quietly stand in for the whole long-term opportunity.
Send me your market-size slide and the calculation behind it.