Rule of 40
Also: Rule of Forty, 40% Rule, Règle des 40, Règle des 40 %, 40er-Regel, Rule-of-40 Score
A SaaS health check: revenue growth rate plus profit margin should reach or exceed 40%. It balances how fast you grow against how much you burn.
What It Is
The Rule of 40 is a benchmark for software and subscription businesses that adds your revenue growth rate to your profit margin. If the sum reaches 40% or more, the business is considered healthy; below that, it raises questions. A company growing 30% with a 10% margin scores 40 and passes. A company growing 15% with a 5% margin scores 20 and needs a plan. Growth and profitability are read together, not in isolation.
Why it matters
Investors and boards use the Rule of 40 to compare companies at very different stages on one line. A young company can score well by growing fast while losing money; a mature one scores well by growing slowly with strong margins. The rule stops leadership from over-optimising one number at the expense of the other, for example chasing growth while cash burn spirals, or protecting margin while competitors take the market. For a CFO it frames spending discipline. For a CMO it justifies acquisition budget when growth is genuinely funding future value. For a CEO it is a shorthand every stakeholder recognises.
How it works
Pick a consistent revenue growth figure (usually year-over-year ARR or revenue growth in percent) and a consistent margin figure (often free cash flow margin or an adjusted operating margin), then add them. Example: your ARR grew 25% and your free cash flow margin was 12%. Your score is 37, just under the bar, so the conversation turns to which lever moves cheapest. The two inputs must use the same period and the same definition every quarter, or the trend line lies to you. Treat it as a directional signal rather than a verdict: an early-stage company deliberately below 40 to capture a market can be making the right call, provided the path back above 40 is explicit and dated.
See also
Frequently asked questions
What is the Rule of 40?
The Rule of 40 is a benchmark for software and subscription businesses: add your revenue growth rate to your profit margin, and the sum should reach 40% or more. A company growing 30% with a 10% margin scores 40 and passes; one growing 15% with a 5% margin scores 20 and needs a plan. The point is that growth and profitability are read together, not separately.
Which revenue and margin figures should go into the calculation?
Use a year-over-year revenue or ARR growth rate as the first input, and a margin such as free cash flow margin or an adjusted operating margin as the second. What matters more than the exact choice is consistency: the same period and the same definition every quarter, otherwise the trend line lies to you. A 25% ARR growth with a 12% free cash flow margin gives a score of 37.
Is a company below 40 automatically in trouble?
No. The Rule of 40 is a directional signal, not a verdict. An early-stage company that deliberately scores below 40 to capture a market can be making the right call, provided the path back above 40 is explicit and dated. What should worry a board is a score drifting down with no stated plan behind it.
Why do investors prefer the Rule of 40 to looking at growth alone?
Because it puts companies at very different stages on a single comparable line. A young company can score well by growing fast while losing money, a mature one by growing slowly with strong margins. The Rule of 40 also stops leadership from over-optimising one number at the expense of the other: chasing growth while cash burn spirals, or defending margin while competitors take the market.
How does the Rule of 40 change the conversation between a CFO and a CMO?
It gives both a shared arbitration rule. For a CFO, the Rule of 40 frames spending discipline; for a CMO, it justifies acquisition budget when growth genuinely funds future value rather than simply consuming cash. When the score lands just under 40, as with 25% growth and a 12% margin, the discussion shifts to which lever, growth or margin, moves at the lowest cost.