What is SOM (Serviceable Obtainable Market)?

SOM (Serviceable Obtainable Market) is the realistic portion of the Serviceable Addressable Market (SAM) that a company can capture in a 3-5 year timeframe, given current competition, resources, distribution, and execution capacity. SOM is the most actionable of the TAM-SAM-SOM trio because it directly informs near-term revenue forecasts.

According to a 2024 PitchBook analysis of Series A pitch decks, SOM is the figure that most directly correlates with founder credibility — investors heavily discount inflated SOM numbers. Strong founders typically present SOM as 1-10% of SAM in the first 3 years, with a clear path to scale.

How SOM works

SOM is calculated by narrowing SAM by realistic execution constraints:

• Competitive intensity — How much of SAM is locked up by incumbents
• Distribution capacity — How many customers your sales/marketing can reach
• Time horizon — Typically 3-5 years
• Brand awareness — How quickly customers will recognize and trust you
• Conversion rate — % of reachable customers who'll actually buy

Example SOM calculation:

• SAM: 1.5M English-speaking SMBs needing social media tools = $900M
• Realistic SOM (3 years): 75k customers (5% of SAM) × $600 = $45M ARR

The 5% capture rate reflects competitive friction, brand-awareness lag, and conversion realities. Even the best startups rarely capture more than 10-15% of SAM in 3 years.

According to a CB Insights study of 1100 startups, the median 3-year revenue at Series A was $5-10M ARR, suggesting most startups capture less than 1% of even modest SAMs in the first 3 years. Realistic SOM forecasts factor this baseline.

SOM should grow over time as the company matures. Year 1 SOM might be $1M, Year 3 $10M, Year 5 $50M, with each year's growth based on funded sales/marketing capacity.

Examples of SOM in practice

Example 1: Linear's developer-tool SOM

Linear (project management for engineers) calculated SOM as engineering teams at 5-200 person tech companies in the US/EU. Year 1 SOM was a few hundred customers; by Year 4, SOM grew to 10,000+ customers reflecting expanded geo and team sizes. Linear's actual revenue tracked SOM closely.

Example 2: Notion's early SOM

Notion's early SOM was English-speaking knowledge workers in tech startups (a small slice of their global TAM). As the company matured and added languages, SOM grew step-function. By 2024, Notion had 30M+ users, validating their original SOM growth trajectory.

Example 3: Indie SaaS founder

A solo founder launching an Etsy seller analytics tool calculates SOM at 5,000 paying customers in 18 months × $30/month = $1.8M ARR. The number reflects realistic single-founder distribution: word-of-mouth, content marketing, and Etsy seller community presence.

When to calculate SOM

Calculate SOM when:

• You're forecasting revenue for the next 3-5 years
• You're sizing fundraising needs against realistic targets
• You're setting board-level revenue and headcount targets
• You're prioritizing distribution investments (which channels will hit SOM faster?)
• You're evaluating competitive moat strength (does your moat let you exceed typical SOM capture?)
• You're justifying a scale-up phase

When NOT to over-focus on SOM

• Early customer discovery — Don't precision-forecast before product-market fit
• Highly experimental product phases — SOM assumes a stable product
• Pure brand-building exercises — SOM is revenue-focused; brand requires longer horizons

SOM vs related concepts

SOM bridges market sizing to revenue forecasts. Pipeline is the operational version of SOM at any given moment.

Common mistakes with SOM

• Inflating SOM to please investors — Sophisticated investors discount inflated SOMs heavily.
• Static SOM that doesn't grow — Year-1 SOM should be much smaller than Year-5 SOM.
• No bridge from SOM to operational plan — How many BDRs, sales reps, and content pieces does the SOM require?
• Ignoring competitive friction — Assuming you'll capture 50% of SAM in 3 years against entrenched competitors.
• One SOM per persona — Different personas have different SOM trajectories.

Frequently asked questions about SOM

What is the difference between SAM and SOM? SAM (Serviceable Addressable Market) is the total market your product can serve given language, geography, and product fit. SOM (Serviceable Obtainable Market) is the realistic portion of SAM you can capture in 3-5 years given competition and resources. SAM is the accessible ceiling; SOM is the believable target.

What's a typical SOM percentage of SAM? For early-stage startups, SOM at year 3 is typically 1-5% of SAM. By year 5, it can reach 5-15%. Mature companies in dominant positions can reach 20-40% of SAM, but this is rare. Higher percentages are usually a sign of inflated SOM or under-stated SAM.

How do I calculate SOM for my product? Start with SAM. Apply realistic capture rate based on your distribution channels, competitive intensity, and brand awareness. Multiply by your annual price. Validate against industry benchmarks: typical Year-3 ARR for similar startups in your space.

What tools support SOM forecasting? CRM (Salesforce, HubSpot, Pipedrive) for pipeline-to-SOM bridge. Mixpanel and Amplitude for activation funnels. Industry research (CB Insights, PitchBook) for benchmarking. Spreadsheet models for scenario planning.

Can SOM exceed competitor revenue? Rarely in early years. SOM forecasts that imply you'll outpace established competitors in 3 years typically lack credibility. Realistic SOM accounts for the time required to build brand, sales motion, and distribution.

How does SOM affect fundraising? SOM directly informs how much capital you need. If your 3-year SOM is $20M ARR and your operational plan requires $15M of cash to hit it, you're sizing a $20M Series A round. Investors back up the calculation against industry burn benchmarks.

How SOM relates to PostKit

PostKit's 3-year SOM is conservative: ~50,000 paying users at an average $39/month plan = $23M ARR. This represents about 0.1% of SAM and reflects realistic indie/SMB SaaS adoption curves. Year-1 SOM is closer to 1,500 users ($700k ARR) consistent with bootstrapped early-traction patterns. Founder Tadeáš Raška has communicated SOM publicly as part of build-in-public posts on X.

Related glossary terms

• TAM (Total Addressable Market) — The market ceiling
• SAM (Serviceable Addressable Market) — The accessible portion
• ICP (Ideal Customer Profile) — Defines who SOM targets
• Product-market fit — Determines SOM achievability
• Competitive moat — Determines whether you exceed typical SOM capture rates

Sources

• PitchBook venture data
• CB Insights startup data
• First Round Review on market sizing