Bottom-Up Market Size Calculator
Size your TAM, SAM, and SOM from real customer counts and prices, then sanity-check the top-down number.
Example scenario—not a forecast or verified benchmark. Enable JavaScript to edit inputs, view charts, save locally and export your analysis.
Example inputs
- Customer segments
- [{"name":"Single-family homeowners","customers":180000,"buyRate":35,"reachable":40,"price":450,"purchasesPerYear":1},{"name":"Property managers","customers":1200,"buyRate":80,"reachable":50,"price":18000,"purchasesPerYear":1},{"name":"Light commercial buildings","customers":6500,"buyRate":60,"reachable":35,"price":3200,"purchasesPerYear":1}]
- Share of SAM you can realistically win
- 15
- Years to reach that share
- 5
- Top-down TAM you have seen quoted (optional)
- 150,000,000
- Your current annual revenue
- 2,000,000
Example results
Bottom-up TAM $58.1M, SAM $24.3M, SOM $3.7M: about $1.7M of winnable revenue above today's $2M.
- TAM (total addressable)
- $58,110,000
- SAM (serviceable)
- $24,348,000
- SOM (15% of SAM)
- $3,652,200
- Headroom vs current revenue
- $1,652,200
- Current share of SAM
- 8.2%
- Growth rate to reach SOM
- 12.8%
- Total buying customers
- 67,860
- Top-down / bottom-up TAM
- 2.58x
What stands out
Single-family homeowners is 47% of your serviceable market
$11.3M of SAM. Concentrate positioning and sales capacity here first.
Top-down TAM is 2.6x your bottom-up TAM
The quoted $150M likely includes segments or geographies you do not serve. Lead with the bottom-up $58.1M with investors.
Reaching SOM requires 12.8% annual growth
From $2M to $3.7M in 5 years.
Next actions
- Build the go-to-market plan around Single-family homeowners: it holds $11.3M of serviceable demand.
- Validate the two biggest drivers (customer count and buy rate in the lead segment) with census/industry data or 10 customer interviews.
- Track share of SAM annually; at 8.2% today, every 1 point of share is worth $243K.
Model assumptions & limitations
- TAM = customers x buy rate x price x purchases per year; SAM applies your reachable %; SOM applies your target share.
- Customer counts, buy rates, and prices are user inputs; verify them against public or industry sources before external use.
- The default 15% target share is a planning assumption, not a benchmark.