Growth rate plus profit margin equals one number every Series B+ board asks for. Drop the two inputs, see the score, and read the investor-grade verdict.
Public SaaS benchmark medians by stage (Bessemer / Meritech 2024 data).
Brad Feld popularized it. Bessemer codified it as the single board-meeting metric for SaaS health:
Rule of 40 score = growth rate (%) + profit margin (%)
The threshold is brutally simple — if the sum is at or above 40, the business is operating in a healthy zone. Investors are willing to fund a money-losing company growing fast, or a slow-growing company that's profitable. The two cancel out. What they won't fund is the third quadrant: slow AND unprofitable.
Caveats: meaningful at $10M+ ARR. Below that, growth dominates and margin is noise.
Drop your email and we'll send the Markdown template most operators use to walk through this number on board calls — including the 3 levers to push when you're below 40, with sequencing.