The Rule of 40, explained
The Rule of 40 says a healthy SaaS company's growth rate plus profit margin should exceed 40%. Learn how to calculate it, why it matters, and the trade-off it captures.
The Rule of 40 is a quick health check for SaaS companies: your revenue growth rate plus your profit margin should add up to at least 40%. It captures the trade-off between growing fast and being profitable.
The formula
Growth rate (%) + Profit margin (%) ≥ 40%Growth is usually year-over-year revenue growth. Profit margin is commonly EBITDA, free-cash-flow, or operating margin — be consistent about which you use. A company growing 60% while burning 15% scores 45 and passes; one growing 20% at 10% profit scores 30 and falls short.
Why it matters
It became a standard benchmark among growth investors because it balances two things that usually trade off. Early on, companies prioritise growth (and accept negative margins). As they mature, growth slows but margins should improve to compensate — keeping the sum above 40.
How to read your score
| Score | Interpretation |
|---|---|
| Above 40 | Healthy balance of growth and profitability. |
| 20–40 | Acceptable but worth improving one side of the equation. |
| Below 20 | Neither growing fast enough nor profitable enough — a red flag. |
Limitations
The Rule of 40 is a rule of thumb, not a law. It is less meaningful at very early stage (tiny revenue makes growth % volatile) and can be gamed by cutting investment. Use it alongside retention, LTV:CAC and payback for a fuller picture.
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Open the SaaS Metrics CalculatorFrequently asked questions
What is the Rule of 40?
It states that a SaaS company's revenue growth rate plus its profit margin should be at least 40%. It balances the trade-off between growth and profitability.
Which profit margin should I use?
EBITDA, operating, or free-cash-flow margin are all used — the key is to be consistent and transparent about which one. Free-cash-flow margin is increasingly preferred.
Does the Rule of 40 apply to early-stage startups?
Less so. At very small revenue, growth percentages are volatile and the rule is noisy. It is most useful for scaled companies (roughly $1M+ ARR and beyond).