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TAM/SAM/SOM Calculator.

A TAM SAM SOM calculator sizes your total addressable market using two complementary approaches. The top-down model starts with total market size and applies serviceable and obtainable percentage filters. The bottom-up model builds from US Census Bureau company counts by industry and employee size band, multiplied by your average contract value and penetration rate. Both models enforce the monotonic funnel invariant where TAM is always greater than or equal to SAM which is always greater than or equal to SOM. Use the sensitivity analysis to see how your obtainable market shifts when ACV varies by plus or minus 20 percent.

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Top-Down Market Sizing

Start with the total market size and narrow down using serviceable and obtainable percentages.

Total market value for your industry

Percentage addressable by your geo, segment, or product fit

Percentage you can realistically capture (capacity + competition)
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How to Use

Get Started in 3 Steps

Step 01

Choose Your Sizing Model

Select the Top-Down tab if you have a total market size figure from analyst reports, or Bottom-Up if you want to build from company counts and average contract value. Both models produce TAM, SAM, and SOM estimates.

Step 02

Enter Your Market Parameters

For top-down, enter total market size and your serviceable and obtainable percentages. For bottom-up, select your industry, company size band, geography, enter your ACV, and set a penetration rate. Company counts auto-populate from Census Bureau data.

Step 03

Review Funnel and Sensitivity

View the TAM, SAM, and SOM funnel visualization with dollar-formatted values. Check the sensitivity table to see how your SOM changes when ACV varies by plus or minus 20 percent. Use both models to cross-validate your market sizing estimate.

How It Works

Under the Hood

The top-down model takes a total market size and applies two sequential percentage filters. SAM equals TAM multiplied by the serviceable percentage, which reflects geographic, segment, and product-fit constraints. SOM equals SAM multiplied by the obtainable percentage, which accounts for your capacity and competitive position. All percentages are clamped to the 0 to 100 range, and obtainable is automatically clamped to not exceed serviceable.

The bottom-up model uses establishment count data from the US Census Bureau County Business Patterns dataset. TAM equals the total company count across all employee size bands in your selected industry and geography, multiplied by your average contract value. SAM narrows to companies in your selected size band only, multiplied by ACV. SOM equals SAM multiplied by your penetration rate. This approach produces reproducible, independently verifiable estimates.

The monotonic funnel invariant ensures TAM is always greater than or equal to SAM, which is always greater than or equal to SOM. If any calculation would violate this ordering, values are clamped downward and a warning is displayed. This prevents logically impossible market sizing where a subset exceeds its superset.

Sensitivity analysis varies the ACV input by plus and minus 20 percent in 5 percent increments while holding all other inputs constant. For each step it recalculates SOM and shows the dollar change from the base case. Rows where the absolute change in SOM is less than one dollar are suppressed to keep the table focused on meaningful variations.

FAQ

Frequently Asked Questions

What is a TAM SAM SOM analysis and why does it matter?
TAM SAM SOM is a three-tier market sizing framework used by startups, investors, and sales teams to quantify revenue opportunity. TAM is the total addressable market representing the entire revenue opportunity if you had 100 percent market share. SAM is the serviceable addressable market, the subset of TAM that matches your geography, product capabilities, and customer segments. SOM is the serviceable obtainable market, the realistic share you can capture given your resources, go-to-market strategy, and competitive landscape. This analysis informs fundraising decks, territory planning, hiring decisions, and sales quota setting by grounding strategy in data rather than intuition.
What is the difference between top-down and bottom-up market sizing?
Top-down market sizing starts with a broad industry figure from analyst reports and narrows it with serviceable and obtainable percentages. It is faster but depends on the accuracy of the starting number and the judgment behind each percentage filter. Bottom-up market sizing starts with the number of potential customers in your target segment, multiplies by average contract value, then applies a penetration rate. It produces more defensible estimates because each input is independently verifiable. Investors and boards generally prefer bottom-up analysis backed by verifiable data. This calculator supports both approaches so you can cross-validate your estimates.
How do I estimate my serviceable addressable market percentage?
Your SAM percentage should reflect the portion of the total market that your product and go-to-market can actually serve. Start by identifying geographic constraints such as regions where you have sales coverage and language support. Then filter by customer segment, removing companies that are too small, too large, or in verticals where your product does not apply. Finally, account for product fit by excluding use cases your platform cannot handle today. Most B2B SaaS companies have a serviceable percentage between 10 and 40 percent of their total addressable market. Document every filter and its rationale so the assumption is auditable and updatable as your business evolves.
What penetration rate should I use for SOM calculations?
SOM penetration rate depends on your go-to-market maturity, competitive density, and sales capacity. Early-stage startups entering a competitive market typically assume 1 to 3 percent penetration of their SAM in the first year. Growth-stage companies with established product-market fit and a scaled sales team may assume 5 to 10 percent. Market leaders in a niche vertical can reach 15 to 25 percent. Avoid using penetration rates above 30 percent unless you have dominant market share and a moat. The sensitivity analysis in this calculator lets you see how SOM changes across different ACV assumptions so you can model best-case and worst-case scenarios.
Where does the industry data in this calculator come from?
The company count data comes from the United States Census Bureau County Business Patterns dataset, which is the most comprehensive source of establishment counts by industry and employee size in the US. This calculator uses data aggregated by 2-digit NAICS industry code across five employee-count size bands. US figures are authoritative public data. The Europe and Asia-Pacific options apply heuristic multipliers based on relative economic size and business density, and are clearly labeled as estimates rather than census-backed figures. All data reflects the most recently available CBP vintage from 2021 and 2022.
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