Market & Business
TAM
Total Addressable Market — the total revenue opportunity available if a company captured 100% of its target market.
TAM stands for Total Addressable Market and represents the maximum revenue a business could theoretically generate if it captured every possible customer in its target market. It's the starting point for market sizing in investor presentations and is almost always presented alongside SAM (Serviceable Addressable Market) and SOM (Serviceable Obtainable Market).
TAM can be calculated top-down (using industry reports and analyst estimates) or bottom-up (multiplying the number of target customers by average contract value). Bottom-up TAM is generally more credible with investors because it's grounded in real unit economics rather than extrapolated macro figures.
The key question isn't just the size of TAM but whether it's growing. A $10B TAM in a growing market is more attractive than a $50B TAM in a shrinking one.
In Practice
A B2B HR software startup targeting mid-market US companies calculates: 50,000 target companies × $12,000 average annual contract value = $600M TAM. A top-down approach might cite the $30B HR software market, but the bottom-up figure is more defensible.
Why It Matters
VCs invest in companies that can become very large — typically $100M+ in revenue or more. If the TAM isn't large enough to support that outcome, even a great team with great execution won't produce the returns a fund needs. Founders should present TAM that's ambitious but credible, not inflated to impress.