What is the Rule of 40 in SaaS?
Introduction
In the SaaS world, every leadership team faces the same relentless dilemma: should you chase aggressive growth or focus on profitability? It’s a balancing act that can make or break a company’s valuation, attract or repel investors, and ultimately determine whether the business scales or stalls.
Enter the Rule of 40 — a simple yet powerful financial benchmark designed to help SaaS companies navigate this high-wire act. At its core, the Rule of 40 states that a company’s revenue growth rate plus its profit margin should total at least 40%.
Why is it one of the most talked-about metrics in SaaS? Because it provides a clean, standardized way to gauge whether a business is scaling sustainably. In a landscape where some companies burn cash for rapid growth and others slow down to drive margins, the Rule of 40 helps leaders and investors quickly assess if that trade-off is under control — or spiraling out of balance.
What is the Rule of 40?
The Rule of 40 is a widely recognized financial health metric used to evaluate the performance and sustainability of Software-as-a-Service (SaaS) companies. The formula is straightforward:
Revenue Growth Rate (%) + Profit Margin (%) ≥ 40%
This dual-metric approach captures both sides of a SaaS business’s financial story: how fast it’s growing and how efficiently it’s converting that growth into profit (or at least limiting losses).
Its purpose? To help executives, investors, and analysts quickly determine whether a SaaS company is striking an effective balance between chasing growth and maintaining profitability — both essential for long-term viability.
While the Rule of 40 feels like a modern SaaS invention, its popularization is often credited to Brad Feld, a seasoned venture capitalist and co-founder of Foundry Group. Feld introduced the idea as a way for boards and investors to cut through the noise of complex financial statements and focus on a single, actionable metric for SaaS companies at various stages of maturity. You can explore the original SaaS formula + calculator popularized by Brad Feld for a deeper look.
How Does the Rule of 40 Work?
At its heart, the Rule of 40 is a financial litmus test — a quick check to see if your company’s growth ambitions and profitability discipline are playing well together.
The Formula:
Revenue Growth Rate (%) + Profit Margin (%) ≥ 40%
Simple math, serious implications.
- Revenue Growth Rate (%): Typically measured year-over-year using Annual Recurring Revenue (ARR) or Monthly Recurring Revenue (MRR).
- Profit Margin (%): Can be calculated a few different ways, but most SaaS companies lean on:
- EBITDA Margin (earnings before interest, taxes, depreciation, and amortization)
- Operating Margin
- Or Free Cash Flow Margin for a cash-centric view
The important part? Whichever profit measure you choose, be consistent when comparing over time or against industry peers.
Interpreting the Results:
High Growth, Low Profit:
A company growing revenue at 50% but with a -10% profit margin still clears the Rule of 40.
Why it works: Early-stage SaaS businesses often prioritize rapid customer acquisition and market share over immediate profitability.
Balanced Growth and Profit:
A business posting 20% growth and a 20% profit margin also hits the mark.
Why it matters: This is the sweet spot mature SaaS firms aim for — sustainable growth paired with healthy margins.
Falling Short:
If a company shows 10% growth and a 15% profit margin (combined 25%), it signals trouble.
What it means: Either growth has stalled without operational efficiency improving to compensate, or profit margins are too thin relative to revenue gains. Either way — it’s a flag for leadership and investors to reassess strategy and resource allocation.
Why the Rule of 40 Matters in SaaS
In SaaS, the tension between scaling fast and turning a profit is relentless. Prioritize growth too aggressively, and cash burn skyrockets. Focus too narrowly on profit, and you risk getting outpaced by hungrier, faster competitors.
The Rule of 40 keeps this tug-of-war in check. It’s not about chasing arbitrary percentages — it’s about preserving strategic balance.
McKinsey has an excellent analysis on the keys to the critical value creation metric if you’d like to dive deeper into how market leaders navigate this balancing act.
Here’s why it matters:
Investor Benchmark:
Investors and venture capitalists use the Rule of 40 to standardize financial health comparisons across SaaS companies, regardless of size or stage. It quickly reveals who’s scaling smart and who’s gambling recklessly.
Executive Decision-Making:
For SaaS leadership, this metric serves as a decision-making compass. Should you double down on growth initiatives? Cut costs? Improve operational margins? The Rule of 40 offers a clear signal when trade-offs need rebalancing.
Growth Strategy Alignment:
As companies evolve, their growth vs. profitability dynamics shift.
- Early-stage SaaS: Growth often takes precedence, even at a loss.
- Growth-stage companies: Balance becomes critical.
- Mature SaaS: Profitability must steadily climb as growth naturally slows.
The Rule of 40 helps SaaS leaders calibrate their priorities at every phase of growth, ensuring they don’t sacrifice long-term health for short-term wins.
How to Calculate the Rule of 40
The Rule of 40’s brilliance is in its simplicity. You don’t need a finance degree or a team of analysts — just two numbers and some basic math.
Step-by-Step:
Step 1: Calculate Revenue Growth Rate
Measure how much your Annual Recurring Revenue (ARR) or Monthly Recurring Revenue (MRR) has increased compared to the previous year.
Formula:
(Current Year Revenue − Prior Year Revenue) ÷ Prior Year Revenue × 100
This gives you your year-over-year (YoY) growth rate as a percentage.
If you’d like a deeper dive into how to calculate it with practical examples, this breakdown is a great starting point.
Step 2: Calculate Profit Margin
Most SaaS companies use EBITDA margin for consistency, but you can also opt for Operating Margin or Free Cash Flow Margin depending on your business model and reporting preferences.
Formula:
(EBITDA ÷ Revenue) × 100
Step 3: Add the Two Percentages
Combine your Revenue Growth Rate and Profit Margin.
If the result is 40% or higher, you’re in the financially healthy zone.
Anything below 40% suggests it’s time to revisit your growth strategy, profitability targets, or both.
Practical Scenarios and Use Cases
The Rule of 40 isn’t one-size-fits-all — it flexes depending on your company’s growth stage and business priorities.
Early-Stage SaaS:
High growth, often with negative profit margins.
Example: +55% growth, -10% EBITDA margin = 45%
Still healthy. At this stage, market capture matters more than margins.
Mature SaaS:
Growth naturally slows, so profitability must pick up the slack.
Example: +18% growth, +25% EBITDA margin = 43%
Balanced, efficient scaling.
Transition Phases:
When growth starts to plateau, and costs rise, leadership must decide whether to double down on customer acquisition or optimize for profitability.
SaaSworthy offers a great overview of Rule of 40 for SaaS explained with real-world cases if you’re navigating this phase.
Key Benefits of Using the Rule of 40
Why do SaaS operators, CFOs, and investors love this metric? Because it delivers big value without complexity.
Quick Financial Health Check:
A single number captures how well your business is balancing growth and profitability.
Encourages Disciplined Scaling:
Prevents companies from chasing reckless growth at the expense of financial sustainability.
Assists in Timing Strategic Pivots:
Whether you’re ramping up for aggressive expansion or tightening up margins, the Rule of 40 helps flag when it’s time to shift focus.
Valuable for Benchmarking:
A standardized, apples-to-apples way to compare your financial performance against competitors, market averages, or investor expectations.
Closing Thoughts
The Rule of 40 isn’t just a SaaS finance buzzword — it’s a practical, high-impact tool for keeping your company’s growth story in check. In a space where it’s tempting to chase explosive revenue at any cost, this metric reminds leadership that profitability matters too.
Whether you’re an early-stage startup burning cash for market share, a growth-stage firm refining your unit economics, or a mature player optimizing margins, the Rule of 40 provides a clear, consistent benchmark for financial health.
It’s not a silver bullet — but paired with other KPIs like customer acquisition cost (CAC), churn rate, and lifetime value (LTV), it becomes a powerful component of your SaaS performance toolkit.
Bottom line:
Use it, track it, and when it starts slipping, pay attention. The Rule of 40 is one of the cleanest signals your numbers can send.
