Total Addressable Market (TAM) Estimator

Build a bottom-up TAM, SAM and SOM from company counts and ACV.

All companies that fit your category.
%
Right size, geo, segment you can serve.
$
%
Share of SAM you can win near-term.
TAM
$1,440,000,000
All companies × ACV
SAM
$504,000,000
35% you can serve
SOM
$20,160,000
4% of SAM

Bottom-up, your near-term obtainable market (SOM) is about $20,160,000, that's the number to plan and pitch against. TAM ($1,440,000,000) is the ceiling story; SOM is what your GTM can actually credibly capture.

Bottom-up TAM (company count × ACV) survives investor scrutiny far better than top-down "1% of a $50B market" hand-waving.

About this calculator

Most TAM slides are top-down guesswork, "the industry is $50B, we just need 1%", and investors have heard that pitch enough times to discount it on sight. This estimator builds the number from the ground up: how many companies actually fit your target profile, how many of those you can realistically reach, and what each is worth, so the market-size story survives real diligence.

How to use it

  1. Enter total target companies, the full count of organizations that fit your ideal customer profile, by industry, size, or geography.
  2. Enter the percentage realistically reachable, the share you can serve given your current geo, segment focus, and go-to-market motion.
  3. Enter average contract value, what a typical customer actually pays per year.
  4. Enter obtainable market share, the percentage of your serviceable market you can credibly capture in the near term, and read TAM, SAM and SOM.

Methodology

TAM (Total Addressable Market) is the full ceiling: total target companies × average contract value. This is the entire theoretical market if you sold to everyone who could conceivably buy.

SAM (Serviceable Addressable Market) narrows that to companies you can actually reach: total companies × reachable percentage × ACV. This accounts for geography, segment, language, or product-fit constraints that TAM ignores.

SOM (Serviceable Obtainable Market) narrows further to what you can realistically win near-term: SAM × your target market share percentage. This is the number a credible go-to-market plan should be built against.

The gap between TAM and SOM is deliberate and large by design, TAM is the story for why the category matters, SOM is the plan for what your specific GTM motion can capture given today's constraints.

FAQ

Why is bottom-up TAM more credible than a top-down percentage claim?

A bottom-up number, built from company counts and a real ACV, gives an investor or exec something they can independently sanity-check: is that company count right, is that ACV realistic. A "we just need 1% of a $50B market" claim gives them nothing to verify, which is exactly why it gets picked apart.

What percentage should I use for "realistically reachable"?

Be honest about constraints your GTM actually has today, language, region, company-size fit, channel reach. A 20-40% reachable share is common for a focused early-stage motion; claiming 80%+ reachable usually signals the ICP definition is too loose.

What obtainable-share percentage is defensible for SOM?

Single digits, typically 1-5% of SAM within a 2-3 year horizon, is standard for a competitive category. Double-digit share claims need a specific reason: a category with few incumbents, a strong existing wedge, or genuine first-mover advantage.

Should TAM, SAM, or SOM drive my hiring and budget plans?

SOM. It reflects what your actual GTM engine can capture given today's constraints. TAM and SAM are useful for framing category size to investors, but planning headcount or spend against them invites the kind of overreach that burns cash chasing a market you can't yet touch.