Rule of 40
The Rule of 40 states that a healthy software company's combined revenue growth rate and profit margin should equal or exceed 40%. It balances the tradeoff between growth and profitability.
Also known as: rule of forty, growth efficiency rule
Formula
Revenue Growth Rate + Profit Margin
Why It Matters
The Rule of 40 elegantly captures the fundamental tradeoff every business faces: you can grow fast and sacrifice profitability, or you can optimize for profit and sacrifice growth. The Rule of 40 says that as long as the sum of your growth rate and profit margin exceeds 40%, you are striking a reasonable balance.
A company growing at 60% with a -20% profit margin scores 40 and passes the test. A company growing at 10% with a 30% profit margin also scores 40. Both represent valid strategies. But a company growing at 20% with a -5% profit margin scores only 15, suggesting it is neither growing fast enough nor profitable enough.
This metric is particularly valuable for SaaS companies navigating the transition from growth-at-all-costs to sustainable growth. Investors increasingly use the Rule of 40 to evaluate whether a company deserves a premium valuation, making it a board-level metric for public and late-stage private companies.
How to Calculate
Add your year-over-year revenue growth rate (as a percentage) to your EBITDA margin or free cash flow margin (as a percentage). If the sum is 40 or greater, you pass the Rule of 40. For example, 30% revenue growth plus 15% EBITDA margin equals 45, which passes. Some practitioners use operating margin or free cash flow margin instead of EBITDA.
Rule of 40 Calculator
Revenue Growth Rate + Profit Margin
Industry Applications
A SaaS company growing at 45% YoY with a -10% EBITDA margin has a Rule of 40 score of 35. After optimizing sales efficiency and reducing hosting costs, they maintain 40% growth with breakeven margins, reaching a score of 40.
Benchmark: Public SaaS companies averaging 40+ score trade at significantly higher multiples; top quartile exceeds 50
A DTC ecommerce brand growing at 25% with 18% EBITDA margin scores 43 on the Rule of 40, demonstrating a balanced growth model that impresses investors compared to peers burning cash for growth.
How to Track in KISSmetrics
Combine revenue growth tracking from KISSmetrics with profitability data from your financial systems. Monitor revenue growth rate monthly using KISSmetrics Revenue Reports, then pair with margin data to calculate your Rule of 40 score quarterly. Set up dashboards that show both components to understand whether changes come from the growth side or the profitability side.
Common Mistakes
- -Using inconsistent margin definitions - EBITDA margin, operating margin, and free cash flow margin will give different results
- -Applying the Rule of 40 to very early-stage companies where growth rate volatility makes the metric less meaningful
- -Treating 40 as a binary pass/fail when it is better used as a spectrum for tracking improvement
- -Ignoring revenue quality - a company can hit 40 with unsustainable growth driven by heavy discounting
Pro Tips
- +Track your Rule of 40 score quarterly to see the trajectory - improving from 25 to 35 over four quarters shows strong progress
- +Use this metric to frame growth vs. profitability tradeoffs in board discussions and strategic planning
- +Companies scoring 40+ with growth above 25% tend to receive premium valuations from investors
- +As growth naturally decelerates, plan for margin expansion to maintain or improve your Rule of 40 score
Related Terms
Revenue
Revenue is the total income generated by a business from the sale of goods or services before any expenses are deducted. It is the top line of an income statement and the starting point for all financial analysis.
Gross Margin
Gross margin is the percentage of revenue remaining after subtracting the cost of goods sold (COGS). It represents the portion of each dollar of revenue available to cover operating expenses and generate profit.
Burn Rate
Burn rate is the rate at which a company spends its cash reserves, typically measured monthly. Net burn rate accounts for revenue, showing how much cash the company loses per month after income.
Monthly Recurring Revenue (MRR)
The predictable revenue a subscription business earns every month from all active subscriptions, normalized to a monthly amount.
Net Revenue Retention
Net Revenue Retention (NRR) measures the percentage of recurring revenue retained from existing customers over a period, including expansions, contractions, and churn. An NRR above 100% means existing customers generate more revenue over time.
See Rule of 40 in action
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