What it means
There are two ways to arrive at a number. Top-down starts big: the market is worth $50 billion, we can win 2% of it, so revenue will be $1 billion.
Bottom-up starts small: we have 40 sales reps, each closes 6 deals a quarter at an average of $25,000, so revenue will be $24 million. The first method is quick and useful for sizing an opportunity; the second is slower but far more honest about what the business can actually deliver with the people, capacity and pipeline it has today.
In corporate budgeting, bottom-up analysis means each department, branch or product manager builds their own numbers, which are then consolidated into the company plan. The strength of this approach is ownership and realism: the people closest to customers know what is achievable.
The weakness is that it can be slow, politically padded (managers build in slack) and blind to big external shifts that nobody at unit level is watching. In investing, a bottom-up analyst studies a company's financial statements, competitive position, management quality and valuation, and buys if the business is good and the price is right, regardless of whether the industry is in favour.
Warren Buffett is the best known example of this style. A top-down investor, by contrast, first decides which countries and sectors will do well, then picks stocks within them.
Most experienced practitioners use both. A bottom-up forecast that is wildly out of line with a top-down sanity check (for example, implying a 60% market share) needs another look.
A top-down number that no team can trace to real activity is a wish, not a plan.
In practice
Real-world examples.
Example
A retailer forecasts sales store by store, using each store's footfall, conversion rate and average basket, then adds the results together instead of applying one growth rate to last year's total.
Example
A software start-up builds its plan from the number of leads the marketing budget can generate, the conversion rate to paying customers and the average subscription, so that every revenue dollar links back to a spending decision.
Example
An equity analyst values a shipping company by studying its fleet, charter rates and debt, and concludes it is cheap even though most investors are avoiding the shipping sector.
Think of it
“Bottom-up starts from the details and builds up-analyzing individual pieces first.
Formula
Calculation
There is no single formula, but a bottom-up revenue build typically looks like this:
Revenue = Number of units x Activity per unit x Value per activity
Worked example. A regional accounting firm wants next year's revenue forecast.
- Partners and senior staff: 12 fee earners
- Billable hours per fee earner per year: 1,400
- Average billing rate: $180 per hour
- Utilisation (hours actually billed as a share of billable capacity): 85%
Revenue = 12 x 1,400 x $180 x 85% = $2,570,400
If the firm plans to hire two more fee earners halfway through the year (adding 1,400 hours between them at the same rate and utilisation), the bottom-up build adds 1,400 x $180 x 85% = $214,200, giving $2,784,600. A top-down check: the local market for such services is about $60 million, so this implies a 4.6% share, which is consistent with the firm's history.Case study
Seen in the real world.
A chain of 35 fitness studios had always budgeted top-down: head office set a 12% growth target and pushed it out to every studio. Two years running, the chain missed its plan, and the studio managers, who had never believed the targets, disengaged. The new finance director switched to a bottom-up build.
Each manager forecast members, average monthly fee, churn and class capacity for their own site. The consolidated result showed 7% growth, not 12%, but it also revealed that eight studios were at capacity and could add classes, while five were losing members to a new competitor.
Head office redirected capital to the eight and put a retention programme into the five. The chain hit 9% growth the following year, above its own bottom-up plan, and managers finally treated the budget as theirs.
Watch out
Common mistakes.
- Adding up unit forecasts without a top-down sanity check. Twenty optimistic sales managers can produce a total that exceeds the entire market.
- Letting units pad their numbers. If bonuses depend on beating budget, managers forecast low; if headcount depends on ambition, they forecast high. Design the process to reduce both.
- Treating bottom-up as slow and therefore skipping it. A one-page driver model per unit is enough for most businesses.
Questions
People also ask.
Is bottom-up better than top-down?
Neither is better on its own. Bottom-up is more accurate for the next 12 to 24 months; top-down is better for spotting big shifts and for quick sizing.
What does bottom-up investing mean in practice?
Reading the accounts, understanding the product and the customers, and deciding what the business is worth before looking at market forecasts.
How often should a bottom-up forecast be refreshed?
Quarterly for most businesses, monthly for fast-changing ones, with the drivers (volumes, prices, conversion rates) updated rather than the totals.
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