Before launching a product or entering a new market, a business needs to ask a fundamental question: How big is the opportunity? Answering this starts with understanding the Total Addressable Market, or TAM.

Think of it as the maximum possible revenue you could make if every single potential customer in the world for your type of product bought from you. It’s the entire universe of demand for what you're selling, with no competition or other limitations. Of course, capturing 100% of a market is unrealistic, but TAM provides a crucial upper limit. It helps founders, investors, and marketing teams gauge the long-term growth potential of a business idea. A large TAM suggests a significant opportunity, while a small one might signal a niche market.

TAM is the whole pie, but you can't eat it all at once. To create a realistic business plan, you need to narrow your focus. This is where two other concepts come in: Serviceable Available Market (SAM) and Serviceable Obtainable Market (SOM).

Serviceable Available Market (SAM) is the segment of the TAM targeted by your products and services which is within your geographical reach. If your TAM is 'all coffee drinkers in the world,' your SAM might be 'all coffee drinkers in the cities where you have cafes.' It’s the portion of the market you can actually serve.

Serviceable Obtainable Market (SOM), sometimes called the Share of Market, is the portion of SAM that you can realistically capture. This takes into account your competition, marketing efforts, and sales channels. Continuing the coffee example, your SOM would be the share of coffee drinkers in your target cities you expect to win over from competitors in the first few years. It's your realistic, short-term sales target.

Here's a quick breakdown of how these three concepts relate to each other.

Understanding the difference between TAM, SAM, and SOM is critical for any business. TAM shows the ultimate potential and gets investors excited. SAM helps define a specific target market and business model. And SOM sets concrete, achievable goals for your sales and marketing teams.

By moving from the vast ocean of TAM to the specific fishing spot of SOM, a company can create a focused strategy, allocate resources wisely, and build a credible plan for growth.

Thinking through these market sizes helps turn a broad vision into a tangible business strategy.