Market Size Calculator

Calculate your Total Addressable Market (TAM), Serviceable Available Market (SAM), and Serviceable Obtainable Market (SOM) from potential customers and revenue per customer. Free with funnel chart and table.

What is Market Size Calculator?

The Market Size Calculator applies the standard TAM/SAM/SOM framework used in startup pitch decks and business plans to estimate your market opportunity. Starting from your total potential customers and average revenue per customer, it calculates your Total Addressable Market, then narrows that down through your Serviceable Available Market and finally your realistic Serviceable Obtainable Market.

Formula

TAM = Total Potential Customers × Average Revenue Per Customer. SAM = TAM × Serviceable Market Percentage. SOM = SAM × Obtainable Share Percentage.

How to Calculate

Enter your total potential customers across the entire market for your product category.
Enter the average annual revenue you'd earn per customer.
Enter what percentage of that total market you can realistically serve (your SAM percentage), based on geography, business model, or channel constraints.
Enter what percentage of your serviceable market you can realistically capture (your SOM percentage), based on competition and go-to-market capacity.
Review your TAM, SAM, and SOM values, plus the funnel chart and table breakdown.

Example

A B2B SaaS company targeting 1,000,000 potential business customers globally, with $120 average annual revenue per customer, has a TAM of $120 million. If the company can only realistically serve 30% of that market (English-speaking, small-to-medium businesses), its SAM is $36 million. If it can realistically capture 5% of that serviceable market in the next few years, its SOM is $1.8 million — a credible near-term revenue target.

Key Benefits

Build a credible bottom-up market size estimate instead of guessing at broad industry percentages
See your full TAM/SAM/SOM funnel with a chart suitable for pitch decks
Understand exactly how geography, channel, and competitive assumptions shrink your addressable market
Export your market size analysis as PDF, Excel, or CSV for business plans or investor materials

Common Mistakes to Avoid

Using top-down market sizing (starting from a large industry report number) instead of bottom-up sizing from actual potential customers
Setting an unrealistically high SOM percentage that ignores competition and limited go-to-market resources
Confusing TAM with SOM in pitch materials — presenting the full addressable market as if it were realistically obtainable revenue

Pro Tips

Always build your market size bottom-up from actual potential customer counts, not top-down from an industry report percentage
Be conservative with SOM — investors are more persuaded by a credible small SOM with room to grow than an inflated one that raises skepticism
Revisit your TAM/SAM/SOM calculation as your business matures, since early assumptions about serviceable and obtainable market often change with real market feedback

Key Terms Explained

TAM (Total Addressable Market): The total market demand for a product category if 100% market share were captured
SAM (Serviceable Available Market): The portion of TAM reachable given business model, geography, or channel constraints
SOM (Serviceable Obtainable Market): The portion of SAM realistically capturable given competition and go-to-market capacity
Bottom-Up Sizing: Estimating market size by multiplying actual potential customer counts by revenue per customer, rather than assuming a percentage of a broad industry figure

Common Use Cases

Building the market size slide for an investor pitch deck
Sanity-checking whether a business idea has enough addressable market to support venture-scale growth
Setting realistic near-term revenue targets based on obtainable market share
Comparing market opportunity across different customer segments or product lines

Frequently Asked Questions

What is the difference between TAM, SAM, and SOM?

TAM (Total Addressable Market) is the entire market demand for your product category if you captured 100% of it. SAM (Serviceable Available Market) is the portion of TAM you can realistically reach given your business model, geography, or distribution channels. SOM (Serviceable Obtainable Market) is the portion of SAM you can realistically win given competition, resources, and go-to-market capacity — this is your actual near-term revenue opportunity.

How do I estimate a realistic SAM percentage?

Consider factors that narrow your addressable market: geographic limitations (if you only serve certain countries or regions), language or localization constraints, industry vertical focus, company size restrictions (e.g. SMB-only or enterprise-only), and any regulatory or compliance barriers. A SAM of 20-40% of TAM is common for focused B2B products; broader consumer products may have higher SAM percentages.

What's a realistic SOM percentage to use?

SOM is typically the smallest slice — often 1-10% of SAM for early-stage companies, reflecting realistic market share you could capture in your first few years given competition and limited go-to-market resources. Established market leaders in a niche might model higher SOM percentages, but investors are skeptical of SOM estimates above 20-30% for new entrants.

Why do investors care so much about TAM/SAM/SOM?

Investors use TAM/SAM/SOM to assess whether a business can grow to the scale needed to return their investment. A large TAM with a credible path through SAM to a meaningful SOM demonstrates that even modest market share translates to significant revenue — while a small TAM makes it mathematically difficult to build a venture-scale business regardless of execution.