TAM, SAM & SOM Explained
TAM, SAM and SOM are three nested measures of market size. TAM (Total Addressable Market) is total demand if you had 100% share; SAM (Serviceable Addressable Market) is the portion your product and model can actually serve; SOM (Serviceable Obtainable Market) is the share you can realistically capture.
Key takeaways
- TAM = the whole market; SAM = the part you can serve; SOM = the part you can win.
- They nest: SOM sits inside SAM, which sits inside TAM.
- Used to size opportunity for strategy, fundraising and planning.
The three layers
| Term | Meaning |
|---|---|
| TAM | Total demand for the product if you had 100% share |
| SAM | The segment your product and model can serve |
| SOM | The share you can realistically obtain near-term |
How to estimate them
Top-down starts from industry figures and narrows by your serviceable segment and realistic share. Bottom-up builds from your ICP — number of target accounts × average contract value — which is usually more credible to investors than a giant top-down TAM.
Frequently asked questions
What do TAM, SAM and SOM mean?
Total Addressable Market (all demand), Serviceable Addressable Market (the part you can serve) and Serviceable Obtainable Market (the part you can realistically win).
How do you calculate TAM?
Top-down from industry data, or bottom-up by multiplying the number of potential customers by average contract value — bottom-up is usually more defensible.
What's the difference between TAM, SAM and SOM?
They nest from largest to smallest: TAM is the whole market, SAM the serviceable portion, SOM the share you can actually capture.
Related service: Define your target market in HubSpot