# TAM SAM SOM

> TAM SAM SOM is shorthand for three market sizes. Total addressable market is all the revenue available if every possible customer bought. Serviceable addressable market is the part your product, geography and business model can reach. Serviceable obtainable market is the share you can realistically win in the next few years. Investors trust bottom-up sizing, built from customer counts and prices, more than percentages of industry reports.

Source: https://delsivo.com/glossary/tam-sam-som · Updated 2026-11-06

## Key takeaways

- TAM is the ceiling, SAM the reachable part, SOM the realistic near-term share.
- Bottom-up sizing (customers times price) is easier to check than top-down.
- Every figure rests on assumptions. State them where an investor can see them.

## TAM SAM SOM with a bottom-up example

A fictional startup sells scheduling software to independent physiotherapy clinics. The figures are illustrative assumptions, not market data.

| Measure | Assumption | Result |
| --- | --- | --- |
| TAM | 40,000 clinics in the countries it could ever sell to, at €3,000 a year | €120 million |
| SAM | 15,000 clinics in its two launch countries that use online booking | €45 million |
| SOM | 1,500 clinics it can win in four years with its sales capacity | €4.5 million |

## What investors check on a market slide

[Delsivo's deck analyzer](https://delsivo.com/deck-analyzer), planned for the Pilot release, extracts market figures with the slide they came from, and they are kept as founder reported until checked.

- Whether the customer count and price come from a source or a guess.
- Whether the price matches what current customers actually pay.
- Whether SOM follows from the sales plan, or is a round percentage of SAM.
- Whether TAM quietly includes adjacent markets the product does not serve.

## Common confusions

- Top-down sizing takes an industry total and a percentage; it often hides the assumptions that matter.
- SOM is not a revenue forecast. It is a reachable share given the plan.
- A large TAM does not make a company venture scale if SAM is small and hard to grow.

## Frequently asked questions

### What is the difference between TAM and SAM?

TAM counts every possible customer for the product. SAM narrows it to the customers your product, geography and model can actually reach today.

### Should a pre-seed deck include TAM, SAM and SOM?

A short, bottom-up version helps. Investors care more about whether the assumptions are reasonable than about the size of the headline number.

### Is bottom-up or top-down market sizing better?

Bottom-up is easier to check, because each input can be tested. Top-down can be a useful sense check alongside it.

## Related pages

- [Market size calculator](https://delsivo.com/tools/market-size-calculator)
- [How to evaluate a pitch deck](https://delsivo.com/how-to-evaluate-a-pitch-deck)
- [Deck analyzer](https://delsivo.com/deck-analyzer)
- [ARR](https://delsivo.com/glossary/arr)