Every pitch deck has exactly one slide where the company, which has eleven customers, claims access to a four-trillion-dollar market. We have built this slide many times, for many fake companies, and we'd like to finally document the methodology, since no deck ever actually shows its work.
Step 1: Start with a real number
You begin, briefly, with integrity. "Global spend on enterprise software is $900 billion," sourced from a real report, with a real footnote, in a real small font. This number is true. It is also the last true number that will appear on the slide.
Step 2: Find a number that contains your number
The trick is not to lie about the big number — it's to find a big number that technically, loosely, under a certain light, contains what you do. You sell scheduling software for dental offices. The global healthcare IT market is $660 billion. Is your product 0.01% of that market? Nobody has checked. Nobody is going to check. The slide does not say "we are a rounding error inside this number." The slide says "healthcare IT: $660B," in a font large enough that the distinction dissolves on its own.
Step 3: Draw three circles
This is the TAM/SAM/SOM slide, and it is always three circles, nested, each one smaller, like a target. TAM is the big circle — everyone on Earth who could theoretically benefit from software, which is everyone, since "benefiting from software" is not a falsifiable claim. SAM is a medium circle, usually TAM divided by some plausible-sounding geography or vertical. SOM is a small circle representing what you'll "realistically" capture, which is realistic only in the sense that it is drawn smaller than the other two — the actual number inside it was chosen by making the circle's diameter look appropriately humble next to the $4 trillion one, not the other way around.
Step 4: Multiply by a number nobody can audit
The move that actually inflates the figure is always a multiplication nobody can check in the room. "50 million SMBs, times our target ACV of $8,000, equals our SAM." Nobody asks where 50 million came from. Nobody asks whether $8,000 ACV describes any customer you currently have, as opposed to a customer you intend to have once the product supports it. The multiplication is real arithmetic performed on two numbers that are not. This is the engine of the whole slide: real math, fake inputs, and a product that looks, from a distance, exactly like diligence.
Step 5: Say "bottoms-up" unprompted
At some point, usually in the Q&A, you will volunteer that this was a "bottoms-up" calculation, as opposed to the inferior top-down kind. This is true in the sense that you did, in fact, build it from smaller numbers upward. It is less true in the sense that "bottoms-up" is widely understood in the room to mean "rigorous," and what you actually built was three guesses stacked like a trench coat pretending to be a methodology.
Step 6: Round up, once, at the end
The final number — the one on the slide, in 80-point type — gets one last adjustment: round up. $3.6 trillion becomes "~$4T." Nobody has ever been accused of fraud for a rounding choice. Everybody has, quietly, used the rounding choice to clear a psychological threshold the unrounded number didn't quite reach.
What investors actually do with this slide
Approximately nothing. Everyone in the room has built this exact slide for their own portfolio companies and knows precisely how it's made, the way a magician watching another magician doesn't gasp at the trick — they clock the sleeve. The TAM slide isn't there to be believed. It's there to establish that you know the genre, that you can perform ambition fluently, in the house style, before anyone gets to the slide that actually matters: the one with eleven customers and a retention curve.
Our recommendation
Build the slide. Everyone expects it, and a deck without one reads as naive rather than honest. Just know what it's for — a genre convention, not a forecast — and don't let your own team start believing the $4 trillion on slide six is a number anyone's actually chasing. The company you're building is the size it is. Slide six is theater. Slide eleven is the job.
If your current TAM slide was built by multiplying "everyone on Earth" by "a price we haven't charged anyone yet," email us at contact@b2bsaas.guru. We'll help you make it bigger. That's the whole service.