TAM Calculator – Total Addressable Market
Estimate your total addressable market (TAM) — the full theoretical revenue opportunity — using a top-down (market × %) or bottom-up (customers × revenue) approach.
Written and reviewed by the CalcBundle editorial team. Transparent formulas · results are estimates, not advice.
Total addressable market
Enter the total market size and a target percentage.
What is a TAM calculator?
TAM — total addressable market — is the total revenue available if your product captured the entire market. It’s the top of the market-sizing funnel used by founders and investors, and the starting point for SAM and SOM.
Two ways to calculate TAM
- Top-down: Total market size × target market %
- Bottom-up: Potential customers × annual revenue per customer
Bottom-up is generally more defensible because it is built from real, checkable numbers rather than a headline market figure and a guessed percentage.
Example
If there are 100,000 potential customers who would each pay $500 a year, your bottom-up TAM is $50,000,000. Top-down, a $1B market with a 5% target segment also gives $50M.
TAM is not realistic revenue
TAM answers “how big could this be in theory?” — not “how much can we make?” Your serviceable available market (SAM) narrows TAM to what your product can actually serve, and your serviceable obtainable market (SOM) narrows it further to what you can realistically win. All three feed into a credible startup valuation.
Top-down vs bottom-up market sizing
Use bottom-up to build a number you can defend line by line, then sanity-check it against a top-down estimate. If the two are wildly different, revisit your assumptions before taking the figure into a pitch.
Frequently asked questions
What is TAM (total addressable market)?
TAM is the total revenue opportunity available if a product achieved 100% market share in its market. It represents the full theoretical size of the market, not what any single company can realistically capture.
How do you calculate TAM?
Two common methods. Top-down: total market size × your target market percentage. Bottom-up: number of potential customers × annual revenue per customer. Bottom-up is usually more credible because it's built from real unit economics.
What is the difference between top-down and bottom-up TAM?
Top-down starts from a large published market figure and narrows it with a percentage. Bottom-up builds the number from how many customers exist and what each pays. Investors tend to trust bottom-up estimates more.
Is TAM the same as realistic revenue?
No. TAM is the total theoretical opportunity. What you can realistically serve is your SAM, and what you can realistically capture is your SOM. Never present TAM as achievable revenue.
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Disclaimer. This calculator provides estimates for informational purposes only. Results are based on the information you enter and the assumptions used by the calculator. Actual financial, tax, business valuation, lending, marketplace or investment outcomes may differ. Consider consulting a qualified professional for decisions involving significant amounts of money. Market-size calculations are estimates and depend on the assumptions and data used. They should not be treated as guaranteed market revenue.