TAM, SAM, SOM: sizing your market in practice

Three acronyms that impress investors — as long as you use them correctly. Here's how to calculate them to prove your market exists and is reachable.

TAM, SAM, SOM answer a question every funder asks: "how much can you actually sell?" These three nested circles move from the total, vast, theoretical market to your concrete, reachable target. Used well, they show you have your feet on the ground. Used badly (a giant TAM, nothing below it), they signal the opposite.

1. TAM — your total market

The Total Addressable Market is the market size if you served 100% of the possible demand for your type of product. It's the big number — but also the least useful on its own. Nobody captures a whole market; the TAM only sets the scene.

2. SAM — your serviceable market

The Serviceable Available Market narrows the TAM to what you can actually serve, given your offering, your geography and your target. It's far more meaningful: it describes the market you're really aiming at.

3. SOM — your obtainable market

The Serviceable Obtainable Market is the share of the SAM you can reasonably capture in the first years, given your capacity, your budget and the competition. It's the most important figure: the one you'll be judged on.

The trap to avoid

The most common mistake: showing a colossal TAM then jumping straight to "we just need to take 1%." The "1%" proves nothing — why 1% and not 0.01%? What the funder wants to see is a SOM built bottom-up: your real capacity × your price × your area. A credible SOM is worth a thousand times more than a spectacular TAM.