Rule of 40
A SaaS health heuristic: a company’s revenue growth rate plus its profit margin should add up to at least 40%.
Vanity Risk
Because "profit margin" isn’t standardized, the Rule of 40 is easy to pass on paper by picking the most flattering margin definition. A company that clears 40 on adjusted EBITDA but misses badly on free-cash-flow margin hasn’t really passed—always pin down which margin is in the sum before trusting the result.
What it measures
The balance between growth and profitability in a single number. The premise is that growth and margin are substitutes a SaaS business can trade against each other: a company growing 60% can afford to burn at a −20% margin, and one growing only 10% needs a 30% margin to compensate—both clear 40. It is a portfolio-level sniff test, not a precise valuation tool. "Profit margin" is not standardized—EBITDA margin and free-cash-flow margin are the two most common choices—so always state which margin you used, because the same company can pass on one definition and miss on another.
Benchmarks
- At or above 40%: the bar for a "healthy" SaaS company under the rule.
- Below 40%: growth and profitability together aren’t keeping pace; the gap points to where to push (faster growth or better margin).
- Originally framed for scaled SaaS (the late-stage investor it came from applied it to companies with at least ~$50M revenue); it is far noisier for very early-stage companies.
Figures reviewed June 2026. Benchmarks vary by source and drift over time — treat as directional and verify against your own data.
What to watch
- Passes on growth, fails on margin: A high-growth, cash-burning profile. Acceptable while growth is genuinely high and capital is available, but the rule says the burn should narrow as growth decelerates—watch that the two move together.
- Passes on margin, fails on growth: A profitable but slow profile. Durable, but the rule flags that growth has become the constraint. The risk is over-optimizing for margin and starving the growth that makes a SaaS multiple worth paying.
In practice
A late-stage SaaS company growing 35% at a −10% margin summed to 25 and missed the rule. Rather than chase growth with more burn, they trimmed unprofitable acquisition channels and lifted margin to +8% while growth held at 33%—a sum of 41. The same business now cleared the bar not by growing faster but by making its existing growth more efficient, which is exactly the trade-off the rule is designed to surface.
Illustrative scenario — a representative composite, not a specific company.
Related: MRR — the recurring-revenue base whose growth rate feeds the rule (often via its annualized form, ARR).; NRR — strong net retention is one of the most efficient ways to raise the growth half of the rule without proportional burn.; Quick Ratio — a complementary efficiency check; the Rule of 40 weighs growth against profit, the Quick Ratio weighs revenue gained against revenue lost.