Why total addressable market (TAM) matters to a first-time founder
Investors use TAM to judge whether your company could ever grow large enough to justify their risk, so a tiny or vague figure can end the conversation early. It also tests your own plan: if every possible customer paying your full price still adds up to a modest sum, the business may suit steady bootstrapped growth rather than venture funding. Building the number bottom-up from real customer counts and prices makes it believable and shows you know who you are selling to.
Examples of total addressable market (TAM)
If 200,000 UK freelancers each paid £240 a year, the ceiling is £48 million. That number answers “is the market large enough to matter”. It does not answer how many of them you can find, or how many will choose you over a spreadsheet.
Common misunderstanding
People present the ceiling as the plan, or they draw it so wide that any company could claim it. A number with no sentence about who is inside it is decoration. The serviceable market is the part you can actually reach. The obtainable part is the share you might win soon.
When to use it
Use it when you need to know whether the market can support the company you are describing. Then go straight to who you can reach. If you cannot get from the ceiling to a list of real buyers, the ceiling is not helping you yet.