A single forecast pretends the future is knowable. Scenarios admit it isn't and plan accordingly. The discipline is simple - build two or three versions of the same forecast under different assumptions, look at how the business behaves across the range, and pre-decide what to do if each scenario unfolds.
Scenario planning - the practice of building 2-3 versions of a financial forecast, each under a different set of assumptions, to understand the range of likely outcomes and pre-plan responses.
The standard three
| What it assumes | What it tells you | |
|---|---|---|
| Base case | Most likely outcome: current growth rate, expected hiring, no major surprises | Where you should expect to land if the business performs to plan |
| Downside | Revenue 20% below plan, key customer churn, slower hiring, expense growth ahead of revenue | Whether you survive a tough year; how low cash gets; what would need to change |
| Upside | Revenue 20% above plan, faster customer growth, ability to invest more | What growth could look like; whether you can fund the upside; what bottlenecks would appear |
Three is the standard because two (good vs bad) is too binary and four or more becomes unwieldy. Base, downside, upside brackets the realistic range without overwhelming.
Vary what you're uncertain about
A common mistake: scenarios that only vary revenue. Most businesses have several uncertain inputs, and the most informative scenarios vary the ones the future actually depends on:
- Revenue growth rate - the obvious one
- Customer concentration - what if your top client leaves?
- Pricing - what if a competitor forces discounting?
- Timing of major events - hire delayed by 2 months, product launch slipped a quarter
- Expense trajectory - what if a key cost rises significantly?
- Conversion rates - paid acquisition getting more expensive
Pick the 2-3 variables that drive the most uncertainty and vary them together in your scenarios.
The point: bracketing outcomes
The value of scenario planning isn't in any single forecast being right - it's in seeing how the business behaves across the range. Specifically:
- Cash runway in each scenario. Does the downside have enough cash to survive? How long can the upside fund itself?
- Profitability in each scenario. Does the downside still break even? At what revenue level do you start losing money?
- Key decisions across scenarios. Does hiring still make sense in the downside? Which expenses could you cut?
Comparing the three side by side surfaces decisions that would otherwise be invisible - like which decisions are robust (they make sense in every scenario) versus fragile (they only make sense in one).
Pre-decide actions per scenario
A scenario without a planned response is a number on a screen. For each scenario, pre-decide:
- Trigger - what observation would tell you this scenario is unfolding?
- Actions - what would you do specifically? Defer hires? Cut marketing? Talk to the bank?
- Sequence - which actions first, which only if needed?
Pre-deciding removes the worst-case dynamic of business management: scrambling to figure out what to do while the bad scenario is already unfolding. The scenario tells you the shape; the playbook tells you the response.
Common mistakes with scenarios
1. Three different revenue numbers, same expenses
The most common error. Real scenarios vary both sides coherently - a downside revenue scenario usually has different hiring, different marketing spend, different decisions.
2. Downside that's actually base case
Optimistic owners often build a "downside" that isn't actually bad - it's the realistic case dressed up as conservative. The downside should make you genuinely uncomfortable.
3. Upside without bottlenecks
Sudden growth has its own constraints - hiring lag, cash tied up in working capital, operations breaking. A realistic upside includes the friction.
4. Building scenarios, never revisiting
Like all forecasting, scenarios drift out of relevance without updates. Revisit quarterly.
Related concepts
- What Is Financial Forecasting - scenarios are forecasting tiers.
- Revenue Forecasting Methods - the input to each scenario's revenue line.
- Expense Forecasting - the expense side of each scenario.
- How Much Cash Reserve Should a Business Have - the reserve size that supports the downside.
- Financial Red Flags Every Owner Should Know - the triggers that tell you a scenario is unfolding.