Definition clarity
Is the term used precisely, or fudged to make a number look better?
Skip or Ship — Glossary
Total Addressable Market
Total addressable market (TAM) is the total annual revenue available if a product achieved 100% market share of everyone who could conceivably buy it — the theoretical ceiling, not a realistic target.
Formula accuracy
Are all the right cost and revenue lines actually included?
Benchmark context
Is the number good or bad without something to compare it against?
Common mistakes
Where do founders usually get this term wrong when they report it?
Practical application
How does this number actually change a Ship, Fix, or Skip verdict?
Key facts
- Definition
- Total addressable market (TAM) is the total annual revenue available if a product achieved 100% market share of everyone who could conceivably buy it — the theoretical ceiling, not a realistic target.
- Category
- Market
- Also known as
- TAM
- Formula
TAM = (number of potential buyers) × (annual revenue per buyer)- Related concept
- Total addressable market
- Calculate it
- TAM/SAM/SOM calculator
What Total Addressable Market means in practice
TAM is the outermost of three nested market figures. It answers a deliberately hypothetical question: if every possible buyer bought, and bought from you, how large would annual revenue be? It exists to establish whether an opportunity is structurally big enough to be worth pursuing — not to forecast revenue.
There are two ways to reach the number, and they are not equally credible. Top-down starts from a published industry figure and applies shrinking percentages, which is fast, unfalsifiable, and correctly distrusted by anyone experienced. Bottom-up starts from a countable population of buyers and a defensible annual spend per buyer, then multiplies. Bottom-up forces you to state assumptions that can be checked, which is precisely why it carries weight.
A TAM is only meaningful alongside its narrower siblings. Quoting a vast TAM without SAM and SOM signals that you have not thought about who you can actually reach, and the number becomes a liability in exactly the conversations it was meant to help.
How it is calculated
TAM = (number of potential buyers) × (annual revenue per buyer)Build both inputs bottom-up. A buyer count you can source and a price you can defend beats any published market-size headline.
Worked example
Compliance software priced at £3,600/year, sold to UK accounting practices.
- Countable buyer population: ~4,200 UK practices with 5–20 staff.
- Annual contract value: £3,600.
- TAM = 4,200 × £3,600 = £15.1m per year.
Takeaway: £15.1m is small for venture funding but excellent for a bootstrapped business — and because both inputs are sourced, the figure survives scrutiny in a way "the global compliance market is worth $40bn" never does.
Common mistakes
- Quoting a top-down industry figure as your TAM. It is unfalsifiable, so experienced readers discount it entirely.
- Confusing TAM with a revenue forecast. TAM assumes 100% share, which no company achieves.
- Counting people who could theoretically use the product but have no budget authority to buy it.
- Presenting TAM alone, with no SAM or SOM to show what you can realistically reach.
Related tool: TAM/SAM/SOM calculator.
Related terms
- Serviceable Addressable Market — Serviceable addressable market (SAM) is the portion of total addressable market you could actually sell to given your business model, geography, language, regulation and target segment — TAM minus everyone you structurally cannot serve.
- Serviceable Obtainable Market — Serviceable obtainable market (SOM) is the share of your serviceable addressable market you could realistically capture within a defined period, given your budget, team, distribution and existing competition.
- Ideal Customer Profile — An ideal customer profile (ICP) is a precise description of the type of customer who gets the most value from your product, is cheapest to acquire, and stays longest — used to focus sales, marketing and product decisions.
Direct answer — Total Addressable Market
Total addressable market (TAM) is the total annual revenue available if a product achieved 100% market share of everyone who could conceivably buy it — the theoretical ceiling, not a realistic target.
Stop reading. Get your verdict.
Describe your idea and the Skip or Ship engine returns a Ship, Fix, or Skip verdict with a full 10-category score breakdown — free, in 30 seconds, no signup.
Frequently asked questions
What is a good TAM for a startup?
It depends entirely on your funding model. Venture investors typically look for a TAM above $1bn because they need outsized outcomes. A bootstrapped business can be highly profitable in a £10–50m TAM, where the lack of competition is often an advantage.
Should I calculate TAM top-down or bottom-up?
Bottom-up, always. Start from a countable buyer population and a defensible price per buyer. Top-down figures derived from published industry reports are treated as noise because the assumptions cannot be checked.
What is the difference between TAM, SAM and SOM?
TAM is everyone who could conceivably buy. SAM narrows to those you can actually serve given your model, geography and segment. SOM is the share you could realistically capture in a few years given your resources and competition.
Related pages
Last reviewed
Ready to pressure-test this idea with live market signals?
Validate your idea