February 3, 2023

The Rule of 40: A Key Metric for Evaluating SaaS Startups

The Rule of 40: A Key Metric for Evaluating SaaS Startups
As a SaaS founder or an investor, the rule of 40 is a critical metric that can give you a glimpse into the future of your business. In this blog, we'll take a look at what is the rule of 40, how it is calculated and why it's so important to keep a close eye on it.

What is the Rule of 40?

The rule of 40 is a metric that balances revenue growth and net operating margin (profits as a percentage of revenue) to give an indication of the future performance of a SaaS business.
A widely used metric in the software-as-a-service (SaaS) industry, it combines revenue growth and net operating margins to provide a holistic view of a company's performance and potential.
To compare your company's R40 with other SaaS businesses, it's important to be aware of these industry trends: 
Top-performing companies with an Annual Recurring Revenue (ARR) between $1 million and $15 million consistently maintain an R40 of 80% or higher, indicating a balanced focus on both unit economics and revenue growth. Even after going public and experiencing a slowdown in YoY ARR growth, the best companies still achieve an R40 of 60%.
The rule of 40 is seen as a key indicator of the health and success of a SaaS business, as it balances the two most critical aspects of a company's financial performance - growth and profitability. While revenue growth is a measure of a company's success in attracting new customers and expanding its business, operating profit margins show the company's efficiency in generating profits from its revenue.

How to Calculate the Rule of 40?

To calculate the rule of 40, you need to have two metrics: revenue growth percentage and net operating margin. Add these two numbers together and if the total is above 40, it indicates a higher chance of success in the long term. However, if the total is less than 40, it could suggest potential liquidity issues in the near future.

Revenue growth is a crucial aspect of a business's success. It shows the ability of the company to increase its sales and attract more customers. A company with a high revenue growth rate is considered to be in a strong position, as it is able to attract more investors and generate more profits. However, revenue growth alone is not enough to ensure the long-term success of a business. 
Profitability is equally important, as it indicates the ability of the company to generate profits from its sales. Net operating margin, also known as net profit margin, is a financial ratio that calculates the amount of profit a company generates from its sales. This metric is expressed as a percentage and indicates the percentage of revenue that is converted into profits. A high net operating margin indicates that the company is efficient in its operations and is generating more profits from its sales.
The balancing act between profitability and growth is a constant challenge for both bootstrapped and VC-backed firms. However, bootstrapped companies have more control over their financial decisions, allowing them to prioritise profitability, while VC-backed companies are often under pressure to prioritise growth to deliver returns to their investors.

Why is The Rule of 40 Important?

The rule of 40 has become increasingly popular in recent years and is widely used by SaaS startups and investors to gauge the health and future prospects of a business. It is a simple, yet powerful metric that helps in evaluating the growth and profitability of a SaaS company.
The rule of 40 is an important metric that not just SaaS founders but also investors keep a close watch on. This metric acts as a correct metric for business performance and gives an indication of the future. 
The reason why the rule of 40 is considered to be an important metric is because it provides a balanced view of the business's performance. The revenue growth percentage indicates the growth of the company, while the net operating margin indicates its profitability. By combining these two metrics, the rule of 40 gives a comprehensive picture of the business's financial health.


In conclusion, the rule of 40 is a critical metric that should be carefully tracked by SaaS founders and investors. It provides a balanced view of the business's revenue growth and profitability, and gives an indication of the future performance of the business. Read our other blog on Growth Capital to understand how to accelerate growth for your early stage start-up.