Serviceable Obtainable Market (SOM)

Serviceable Obtainable Market (SOM) is the portion of your Serviceable Addressable Market (SAM) that you can realistically win in the near to mid-term, given your competitive position, sales capacity, and budget. In the classic TAM, SAM, SOM hierarchy, TAM is the total theoretical demand, SAM is what you can serve, and SOM is the share you can practically capture in the next few years.

SOM is an estimate, not a list

University market-sizing guides describe the three layers in revenue terms. The University of Utah technology licensing office, for example, defines TAM as 100% of the revenue from all possibly related customers, SAM as 100% of the revenue from all target customers, and SOM as the percentage of SAM revenue you realistically expect to be able to capture, in a best-case scenario. A UMass Lowell market-sizing session frames SOM as the realistic market share you can obtain given competition, countries, and sales and distribution channels, for a specific year. The Utah guide also notes that market sizing requires assumptions, and those assumptions need to be justified.

An account list is different. It is a working set of companies and contacts your team will pursue. It is usually bigger than the number of customers in your SOM, because most accounts you work will not buy, and smaller than your SAM, because you cannot work every account at once.

A hypothetical TAM, SAM, and SOM calculation

All figures here are hypothetical. Imagine a company that sells shipment-scheduling software to logistics companies for $24,000 per customer per year.

• TAM: 40,000 logistics companies worldwide could use the product. 40,000 x $24,000 = $960 million in annual revenue.
• SAM: today the company can serve only US firms with 50 to 500 employees that use one of the two systems it integrates with, about 6,000 companies. 6,000 x $24,000 = $144 million in annual revenue.
• SOM, three-year horizon: the team expects to create 150 qualified opportunities a year and win 20% of them, which is 30 new customers a year. Ignoring churn, that is 90 customers by the end of year three, or 90 x $24,000 = $2.16 million in annual recurring revenue. That is 1.5% of SAM.

The assumptions are explicit: price, the SAM filters, opportunity volume, win rate, a three-year horizon, and no churn. Change any of them and the SOM changes, so review it as your real win rates and capacity become clearer.

How the outreach account list follows from SOM

Continuing the hypothetical example, suppose the team’s past data shows roughly one qualified opportunity for every 8 accounts it works. To create 150 opportunities a year, it needs to work about 1,200 accounts a year (150 x 8). Those 1,200 accounts are drawn from the 6,000-company SAM and prioritized by ICP fit and buying signals.

Notice what the list is and is not. It is 1,200 accounts to pursue. It is not the 90 customers or $2.16 million that make up the SOM, and it is not the whole SAM. If the list cannot produce enough opportunities because coverage, response rates, or win rates fall short, the honest fix is to lower the SOM estimate or add capacity, not to relabel the list as the obtainable market.

In B2B sales development, market sizing becomes operational when you derive an actual prioritized list of accounts and contacts from it. That list is not your SOM: SOM is the revenue or number of customers you expect to win, and the list is the set of accounts you will work to get there. Instead of saying “we sell to mid-market SaaS companies globally,” a disciplined team defines a focused universe within its SAM, such as “3,000 US-based SaaS companies with 50-500 employees using Salesforce and hiring SDRs,” then narrows it to an active list that its SDR headcount, territory coverage, and channel mix can realistically work.

SOM matters because it connects strategy to day-to-day prospecting. Overly inflated markets produce bloated, low-quality lists and create the illusion of opportunity, while reps still spend 60%+ of their time on non-selling tasks. A well-defined SOM keeps list-building, outbound sequences, and SDR activity tightly focused on the accounts most likely to convert, shortening sales cycles and improving win rates.

Modern sales organizations also use SOM as a capacity planning and forecasting tool. Realistic SOM models, built from your own win rates, sales capacity, and deal sizes, stop leadership from assuming, for example, 20% penetration in year one and over-hiring SDRs or over-investing in channels. By anchoring outreach volume, coverage models, and pipeline targets to SOM, revenue teams can model how many accounts, contacts, and touches are required to hit opportunity and booking goals.

Over time, SOM has evolved from a slide in an investor pitch to a living, data-driven construct owned jointly by RevOps, marketing, and sales development. Teams now refine SOM continuously using firmographic, technographic, and intent data, plus feedback from SDR conversations and win/loss analysis. AI and modern data vendors make it easier to test new micro-segments, expand into adjacencies, and quickly update lists as markets shift. In this context, SOM remains a market-sizing estimate, but it should shape B2B list-building, territory design, and outbound sales execution.