Rule of 40 Calculator for Growth Stock Investors

The Rule of 40 is a simple benchmark used to assess whether a growth company is balancing expansion and profitability effectively.

Our Rule of 40 calculator combines revenue growth and profitability into one simple score. If the combined total reaches 40 or more, the business is often seen as meeting a healthy growth-quality benchmark.

Read our full Growth Investing tutorial: Using the Rule of 40 with Practical Examples

How to Use the Rule of 40 Calculator

Rule of 40 is most commonly used by SaaS and software companies, where investors often accept lower short-term profits in exchange for strong revenue growth. The core idea is that a high-quality growth company should not be judged only on profit margins or only on growth. It should be judged on both together.

Start by entering the company’s year-over-year revenue growth rate as a percentage.

Next, enter the profitability margin you want to use. Many investors use free cash flow margin, EBITDA margin, or operating margin. The key is to be consistent when comparing companies.

Then select the margin type so the output clearly shows what profitability measure was used. You can also adjust the target threshold if you want to use something stricter or more flexible than the classic benchmark of 40.

Once entered, the calculator shows:

• The Rule of 40 score
• The target threshold
• How far above or below the target the company is
• And a quick screening verdict

The best use of the Rule of 40 is as a high-level quality screen for growth companies before moving on to deeper work.

Rule of 40 Formula Explained

The formula is very simple:

Rule of 40 Score = Revenue Growth Rate + Profit Margin

For example:

• revenue growth = 25%
• free cash flow margin = 18%

Then:

Rule of 40 Score = 25 + 18 = 43

That company would score 43, which is above the classic 40 benchmark.

The logic is that a company can offset somewhat lower profitability if growth is very strong, and somewhat slower growth if profitability is strong. What matters is the combined business quality profile.

Rule of 40 Worked Example

Assume a company reports:

• revenue growth = 30%
• EBITDA margin = 12%

Now calculate the score:

Rule of 40 Score = 30 + 12 = 42

This company scores 42, which is above the standard threshold of 40.

That suggests the company is balancing growth and profitability reasonably well.

Now compare that with another company:

• revenue growth = 18%
• operating margin = 10%

Then:

Rule of 40 Score = 18 + 10 = 28

That company scores 28, which is well below the Rule of 40 benchmark. It may still become a strong business later, but at this point, it looks weaker under this particular growth-quality screen.

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How to Interpret the Result

A Rule of 40 score above 40 is generally seen as a positive signal. It suggests the company is combining enough growth and profitability to meet a widely used benchmark for healthy software or growth businesses.

A score around 40 is usually considered acceptable or competitive. The company may not be exceptional, but it is at least meeting the standard investors often look for.

A score well below 40 suggests the company may be too weak on growth, too weak on profitability, or both.

The key limitation is that the Rule of 40 is only a high-level screen. It does not tell you:

• whether the revenue is high-quality
• whether margins are sustainable
• whether stock-based compensation is excessive
• whether dilution is rising
• whether the valuation already prices in perfection

That is why the Rule of 40 works best as a quick first filter. It helps you identify which growth companies warrant deeper research, but it should always be paired with broader analysis of retention, cash-flow quality, competitive advantage, and valuation.