Sales & marketing · Calculator companion · By K Imports
TAM, SAM and SOM market sizing: practical guide
This guide explains how to use the Count.ie tam, sam and som market sizing. Build a bottom-up market estimate from potential accounts and annual customer spend. Follow the inputs, method and worked example below, then compare your own scenario.
Guide written .
Open the TAM, SAM and SOM market sizing calculatorWhat to prepare
- Define the event, conversion, customer and attribution period before collecting data.
- Use spend and outcomes from the same reporting window.
- Distinguish revenue, contribution profit, recurring revenue and customer lifetime assumptions.
Understand the inputs
The calculation method
TAM = accounts × annual revenue per account. SAM applies the serviceable share; SOM applies attainable share to SAM.
Worked example
Illustrative inputs and their result.
Example inputs
- Total possible accounts
- 20000
- Annual revenue per account (€)
- 1500
- Serviceable share of accounts (%)
- 30
- Attainable share of serviceable market (%)
- 5
Calculated example result
- Total Addressable Market
- €30,000,000.00
- Serviceable Market
- €9,000,000.00
- Obtainable Market
- €450,000.00
How to interpret the result
A marketing metric depends on its attribution and cost definitions. A favourable ratio is not proof that advertising caused every sale or that future customers will behave the same way.
Compare campaigns with the same attribution window and outcome definition. Test a lower conversion rate or shorter retention period before extrapolating a promising result.
Common mistakes to avoid
- Do not double-count a customer or conversion reported by multiple channels.
- Revenue is not the same as profit available to fund acquisition.
- Small samples and changing cohorts can produce unstable comparisons.
Assumptions and sources
Account counts, customer spend and market share are assumptions that need evidence and competitive assessment.
If your case falls outside this scope, use a more suitable calculator or contact us about an unclear method.