What the TAM SAM SOM calculator produces
You get three market size estimates built from numbers you can explain to an investor. TAM is the total yearly revenue if every target customer bought from you. SAM is the part you can reach with your current product and channels. SOM is the share you could realistically win in about three years.
The calculator shows the formula behind each figure, so you can defend the estimate in a meeting and adjust it when an investor challenges an assumption.
How it works
Enter the number of companies that match your customer profile and what each would pay you per year. The calculator multiplies them to get TAM. It then applies the percentage you can reach to get SAM and the percentage you can win to get SOM. Results update as you type.
This bottom-up method starts from customers you can count, which is why many investors find it more credible than quoting a large industry report.
What a good output looks like
Target customers: 28,000 SaaS companies with 10 to 200 staff Annual contract value: $6,000 TAM = 28,000 × $6,000 = $168.0M Reachable share: 40% (English-speaking markets, current integrations) → SAM = $67.2M Winnable share in 3 years: 5% → SOM = $3.4M
Every number here is invented. A good output explains where the customer count comes from and why each percentage is realistic.
How to use your market size
- Put the three figures on one slide with the formula and the source of your customer count.
- Write one sentence explaining each percentage so investors can follow your reasoning.
- Keep a note of your assumptions and update them as you learn from sales.
- Compare SOM with your revenue plan to check the two tell the same story.
Who it is for and how to choose better assumptions
The calculator is built for founders preparing a market slide for a pre-seed, seed or Series A deck, and for anyone checking whether a new segment is large enough to pursue. It works best when you can describe your customer profile in terms someone else could count.
- Define the customer by attributes you can look up, such as industry, size and region, so the count can be checked.
- Use the price you charge or plan to charge today, since investors compare it with your current deals.
- Base the reachable share on the channels and languages you serve now.
- Keep the winnable share modest and explain it with your sales capacity and early results.
TAM SAM SOM calculator questions
What do TAM, SAM and SOM mean?
TAM is total addressable market, SAM is serviceable addressable market and SOM is serviceable obtainable market. Together they show the full opportunity, the part you can reach and the part you can win.
Why use a bottom-up calculation?
Bottom-up sizing starts from customers you can name and the price you charge, so every figure traces back to an assumption you can explain.
What percentage should I use for SOM?
Use a share you can support with your sales capacity and early results. Explain the reasoning on your slide so investors can judge it.
Is the calculator free?
Yes. The results calculate instantly as you type and no email is needed to see them.
Where can I find the number of target customers?
Founders often use public company databases, industry association lists or professional network searches filtered by industry, size and region. Note the source on your slide so investors can check it.