The Rule of 40: What It Is and Why Every SaaS Company Should Track It
What is the Rule of 40?
The Rule of 40 is a simple formula that measures the balance between growth and profitability in a SaaS business:
Rule of 40 = Revenue Growth Rate (%) + Free Cash Flow Margin (%)
If the combined score is 40 or above, the company is considered healthy. It's a single number that captures the tradeoff every SaaS company faces: growing fast burns cash, but profitable companies often grow slower.
Why It Matters
Early-stage SaaS companies are almost always unprofitable — they're investing heavily in growth. That's fine, as long as the growth rate justifies the burn. A company growing 80% with -30% FCF margin has a Rule of 40 score of 50 — healthy.
But a company growing 15% with -20% FCF margin scores 35 — they're neither growing fast nor profitable. That's the danger zone.
Investors use the Rule of 40 as a quick screen. It answers: is this company growing fast enough to justify its losses, or profitable enough to justify its slower growth? Companies that score well command higher valuation multiples.
How to Calculate It
You need two numbers:
Revenue Growth Rate: Year-over-year ARR or revenue growth, expressed as a percentage. If your ARR grew from $5M to $6.5M, your growth rate is 30%.
Free Cash Flow Margin: Free cash flow divided by revenue, expressed as a percentage. If you generated $500K in FCF on $6.5M revenue, your FCF margin is 7.7%.
Rule of 40 = 30% + 7.7% = 37.7 — close but below 40.
Some companies use EBITDA margin instead of FCF margin. Either works, but be consistent and know which one you're using when comparing to benchmarks.
Benchmarks
Based on public SaaS company data:
- Elite (60+): CrowdStrike (59), Datadog (58), Snowflake (58) — high growth AND strong margins
- Healthy (40-60): Most well-run public SaaS companies fall here
- Below threshold (30-40): Not failing, but investors will scrutinize closely
- Concerning (below 30): Neither growing fast enough nor profitable enough
For earlier-stage companies ($1-10M ARR), a Rule of 40 score below 40 is common and acceptable — you're investing in growth. But the trajectory matters. Are you improving quarter over quarter?
The Rule of 40 at Different Stages
Early stage ($0-5M ARR): Growth should dominate. A company growing 100% with -40% margins scores 60 — excellent. At this stage, growth rate matters far more than profitability.
Growth stage ($5-30M ARR): Margins should start improving. Growth naturally decelerates, so profitability needs to pick up the slack. Target: growth 40-60%, margins improving toward breakeven.
Scale ($30M+ ARR): The balance shifts. Growth rates settle to 20-30%, and FCF margins should be 15-25%+. This is where the Rule of 40 becomes a true benchmark rather than just a guideline.
How to Improve Your Score
You can improve the Rule of 40 from either side:
Increase growth: Improve NRR so existing customers contribute more revenue. Reduce churn so you keep more of what you've already sold. Optimize your sales efficiency (magic number) to get more ARR per dollar of S&M spend.
Improve margins: Increase gross margin by reducing hosting and support costs. Improve sales efficiency to lower CAC. Reduce discretionary spending that isn't directly driving growth.
The most capital-efficient path is usually improving retention — every dollar retained drops straight to both growth and profitability.
Track Your Rule of 40
See how public SaaS companies score on the Rule of 40 in our free benchmarks library. Track your own growth and retention metrics with ARRGuide.