What is Serviceable Obtainable Market (SOM)?

Serviceable Obtainable Market (SOM) is the share of your Serviceable Addressable Market that you can genuinely win in the next few years, given competition, your budget, and your team. It's the most realistic and most useful of the three market-size numbers.

Where TAM is the dream and SAM is the reachable market, SOM is the forecast — the slice you can actually grab. It directly informs your revenue targets and what kind of business you're building.

How to estimate SOM

A grounded approach starts from your real capacity: how many customers your sales and marketing can reach and close in a year, multiplied by your price. Then sanity-check it against the market share competitors hold in similar categories.

If three established players already split 80% of a market, assuming you'll take 40% in year two isn't a forecast, it's a fantasy. SOM keeps expectations honest.

• Build SOM bottom-up from your actual sales capacity, not a percentage guess.
• Account for incumbents — they won't hand you their customers.
• A 1–5% share of SAM in the first few years is often a realistic starting point.

Why SOM matters for validation

SOM is the number that separates a hopeful pitch from a credible plan. It's what you should base hiring, fundraising, and revenue goals on. If a realistic SOM can't support the business you want to build, that's a signal to rethink the idea before you commit.