When launching a new product or business, one of the first questions you'll face is: how big is the market? Answering this question starts with understanding the Total Addressable Market, or TAM.

Think of it as the maximum possible revenue you could make in a year if you were the only company selling your product and every single potential customer bought it. It’s the theoretical ceiling for your business. If you were selling a new type of surfboard, your TAM would be the total amount of money spent on all surfboards by everyone in the world in a single year. It's a big, optimistic number.

Calculating TAM is crucial for business strategy. It helps founders and investors gauge the potential scale of a business. A massive TAM suggests a significant growth opportunity, while a small TAM might signal a niche market that can't support a large company. It sets the upper limit for your ambitions and helps you decide if an idea is worth pursuing.

Of course, no business captures 100% of its market. You have competitors, geographical limitations, and specific product features that don't appeal to everyone. That's why we need to narrow down from the big-picture TAM to more practical figures. Two other key concepts help with this: SAM and SOM.

Your Serviceable Available Market (SAM) is the slice of the TAM that you can actually serve. Let's go back to the surfboard company. While the TAM is global, maybe your company only ships to the United States. Your SAM would be the total annual revenue from surfboard sales just within the U.S.

Finally, the Serviceable Obtainable Market (SOM) is the portion of your SAM you can realistically win. This is your target for the near future, taking into account your competition, marketing budget, sales team, and brand recognition. For the surfboard company, if the U.S. market (SAM) has several established competitors, your SOM might be the 2-3% of the market you aim to capture in your first couple of years.

Together, these three metrics provide a powerful framework. TAM shows the grand potential. SAM grounds that potential in the reality of your business model. And SOM sets a concrete, achievable target.

Thinking through TAM, SAM, and SOM helps you build a more credible business plan and a smarter go-to-market strategy. It forces you to be both ambitious about the long-term vision and realistic about the short-term goals.

Ready to check your understanding?

Understanding these market sizing concepts is the first step in assessing any business opportunity. It provides a clear view of the landscape, from the entire world of possibilities to the immediate hill you need to climb.