In revenue modeling, which approach is more commonly used in practice?

• A. Bottoms-up: start with individual products/customers and estimate average sale value and growth rate
• B. Top-down: start with overall market size only
• C. Hybrid approach with no clear preference
• D. Top-down: start with market share and growth rate only

Answer: (A)

Revenue modeling is most reliable when you anchor the forecast in the actual drivers you can control and observe—the unit economics tied to products and customers. Building up the numbers from individual products or customer segments, and estimating things like average sale value, number of customers, and how those figures grow over time, keeps the model connected to real business dynamics. This bottom-up approach lets you validate assumptions against historical data, test how changes in pricing, volume, or churn ripple through revenue, and present a credible path to scale. It’s also the approach investors and lenders tend to trust because the forecast can be traced to concrete drivers and supported by the operating plan.

Starting from the overall market size alone ignores the company’s specific performance and unit economics, so it can produce numbers that look impressive but aren’t defensible. A hybrid approach can be useful for sanity checks, but in practice the backbone of a revenue model is typically built bottom-up. Starting with market share and growth rate only—without grounding in actual sales drivers—lacks the credibility of a driver-based forecast.