The TAM slide is where Foundurrs go to church. It is the one page that has a number on it, which makes it feel like finance, and the number is a fantasy, which makes it feel like home.

The method

Step 1. Identify a human problem. Eating. Sleeping. Being lonely. Having a calendar.

Step 2. Count the humans. All of them. Include the ones who are busy, broke, uninterested, or dead. Death is a TAM expansion if you are building for legacy, and you are always building for legacy.

Step 3. Multiply by a price no one has agreed to pay. Round up. Rounding down is a scarcity mindset.

Step 4. Write “conservative.” This word, placed under a number the size of Belgium’s GDP, is how you signal that you are the reasonable one in the room.

Worked example

You have built a notes app. There are eight billion people. Some of them think thoughts. That is the SAM. Some of them write the thoughts down. That is the SOM. You will take 2 percent in year three. You have not taken one person in year zero. This is fine. Year zero is for positioning.

If an investor frowns, add AI. The TAM of “people who think” becomes “people whose thoughts can be inferred.” Congratulations. You have invented surveillance and called it a wedge.

A smaller, more humiliating number

Here is a better slide. How many people used it last week. How many came back. How many would be sad if it disappeared. If those numbers are three, one, and your roommate, you do not have a TAM problem. You have a product. Or you don’t. Either way, stop counting the dead.