The Rule of 40 is a simple financial benchmark used mostly for Software as a Service [SaaS] and technology companies.
It says:
Revenue Growth Rate + Profit Margin should be at least 40%.
In simple terms, a good software company should have a healthy balance between growth and profitability.
Formula
Rule of 40 = Revenue Growth Rate + Profit Margin
The profit margin is often measured using:
EBITDA [Earnings Before Interest, Taxes, Depreciation, and Amortization] margin
or sometimes:
Free Cash Flow [FCF] margin
Example 1: Fast-Growing Company
Suppose a SaaS company has:
Revenue Growth Rate = 35%
EBITDA Margin = 10%
Rule of 40 score:
35% + 10% = 45%
This company passes the Rule of 40 because 45% is above 40%.
Even though its profit margin is not very high, its strong revenue growth makes up for it.
Example 2: Slower-Growing but Profitable Company
Suppose another company has:
Revenue Growth Rate = 12%
EBITDA Margin = 30%
Rule of 40 score:
12% + 30% = 42%
This company also passes the Rule of 40.
It is not growing very fast, but it is highly profitable.
Example 3: Company That Fails the Rule
Suppose a company has:
Revenue Growth Rate = 20%
EBITDA Margin = 5%
Rule of 40 score:
20% + 5% = 25%
This company fails the Rule of 40.
It is growing, but not fast enough to justify its low profitability.
Why the Rule of 40 Matters
The Rule of 40 helps investors judge whether a company is using its money wisely.
A young company may spend heavily on sales, marketing, and product development, so its profit margin may be low or even negative.
That can be acceptable if revenue is growing very fast.
A mature company may grow more slowly, but it should usually produce stronger profits.
The Rule of 40 brings these two ideas together.
Easy Way to Remember It
A company can pass the Rule of 40 in two ways:
High growth + low profit
or
Low growth + high profit
The key idea is balance.
A company does not need to be perfect in both areas, but the combination should be strong.
Important Warning
The Rule of 40 is a useful shortcut, but it is not a complete investment analysis.
You should still look at:
Revenue quality
Customer retention
Debt
Cash flow
Competitive advantage
Valuation
Management quality
A company can pass the Rule of 40 and still be overvalued.
A company can fail the Rule of 40 temporarily and still become a great long-term business.
Bottom Line
The Rule of 40 is a quick way to measure whether a software or technology company has a healthy balance between growth and profitability.
If growth rate plus profit margin is 40% or higher, the company is generally considered financially healthy.
