Market Size Calculator (TAM/SAM/SOM)
Sizing your market opportunity.
Calculate TAM SAM SOM market sizing for business planning. Enter tam total to see market size using tam/sam/som methodology with target market share.
What this tool does
This calculator models a market opportunity by breaking it into three successive layers. Starting with your total addressable market (TAM), it applies your serviceable available market percentage to find the realistic slice you can reach (SAM). It then applies your serviceable obtainable market percentage to SAM to estimate the portion you could realistically capture (SOM). Finally, it multiplies SOM by your target market share percentage to show projected revenue at that penetration level. The result illustrates how each assumption compounds downward through the cascade. Key drivers are your SAM and SOM percentages—small changes here create large shifts in final revenue. This type of layered model is common when evaluating new product lines or geographic expansion. Note: the output estimates based on your inputs and does not account for competitive dynamics, execution risk, or market changes over time.
Quick answer: with the default values, the result is $100,000,000.00 (Serviceable Obtainable Market (SOM)). Adjust the values below for your own figures.
Enter Values
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TAM SAM SOM Calculator
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Formula Used
Spotted something off?
Calculations or display — let us know.
Disclaimer
Results are estimates for educational purposes only. They do not constitute financial advice. Consult a qualified professional before making financial decisions.
Market sizing uses three layers: TAM (Total Addressable Market - everyone who could theoretically buy), SAM (Serviceable - within your geographic/product reach), SOM (Obtainable - realistic near-term). This calculator works through all three.
10B TAM × 20% SAM (your region/category) × 5% SOM (realistic 3-year reach) = 100M SOM. Target 2% market share in SOM = 2M target revenue. Fundable for most seed-stage businesses.
Investors want realistic SOM, not impressive TAM. A 100M TAM with credible 5-10% capture story beats 10B TAM with vague 'we'll get 1%'. Ground each layer with specific reasoning.
A worked example
With the defaults: tam of 10,000,000,000, sam of tam of 20%, som of sam of 5%, target market share of 2%. The tool returns 100,000,000.00. You can adjust any input and the result updates as you type — no submit button, no reload. That's the real power here: seeing how sensitive the output is to one or two assumptions.
What moves the number most
The result responds to TAM (Total), SAM % of TAM, SOM % of SAM, and Target Market Share. Not every input has equal weight. Adjusting one input at a time toward extreme values shows which ones move the result most.
The formula behind this
TAM → SAM → SOM cascade. SAM = TAM × SAM %. SOM = SAM × SOM %. Target revenue = SOM × share %. Everything the calculator does is shown in the formula box below, so you can check the math against your own spreadsheet if you want.
Using this as a check-in
Running this every three months shows a trend rather than a single snapshot. One reading shows where things stand; several over time show whether they are improving. The trend matters more than any individual reading.
What this doesn't capture
The result reflects only the inputs you provide and the assumptions built into the formula. It is a simplified model rather than a complete picture, and factors specific to your situation may matter just as much.
£10,000,000,000 TAM × 20% SAM × 5% SOM × 2% = $100,000,000.00.
Inputs
| TAM (Total) | $10,000,000,000.00 |
|---|---|
| SAM (Serviceable) | $2,000,000,000.00 |
| Target Revenue | $2,000,000.00 |
| Target Share | 2.00% |
This example uses typical values for illustration. Adjust the inputs above to match a specific situation and see how the result changes.
Sources & Methodology
Methodology
The calculator applies a cascading market segmentation model to estimate addressable revenue. It begins with the total addressable market (TAM) and applies the serviceable addressable market (SAM) percentage to derive the SAM value. It then applies the serviceable obtainable market (SOM) percentage to SAM to calculate the SOM figure. Finally, it multiplies the SOM by your target market share percentage to project potential revenue. The model assumes constant percentages throughout the cascade and treats market segments as independent proportions. It does not account for market growth, competitive dynamics, market share volatility, or changes in segment definitions over time.
References
Frequently Asked Questions
Realistic SOM percentages?
What is the difference between TAM, SAM, and SOM?
Why does a small change in my SAM or SOM percentage cause such a large shift in projected revenue?
Can this calculator be used for geographic expansion into a new market?
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